Well fellows, I was NOT joking when saying that someone should pack the Tek (and others) GPIB software and have it reversed and reproduced properly using Web Serial API (sadly, only for Chrome derivatives, because Mozilla is busy with more woke shite).
I give it a try, and after a few road bumps, like activating ONLY if the page is served via a secure connection with a recognized certificate, it started to work surprisingly well.
Well, I know that most will rather sunk their money and effort budged in "original and supported NI" 8-bit ISA cards and, obsolete, but expensive PC, that will need fiddling with configuration jumpers and HIMEM.SYS, instead of paying a pittance to have it reversed and having used from every machine know to man via cheap GPIB adapter like AR488 (thanks again @artag & @WaveyDipole for the wonderful project).
Speaking of which, I do have a couple of buffered AR488 and a couple of un-buffred ones, that you either as kit or soldered, mostly at cost, sometimes I may put them on on B/S/W topic.
Yes please!

I can't help much with the software and programming side of things (I program with a soldering iron.

) but I gave a good selection of TDS 600 and 700 series scopes, plus the required gear to complete the adjustments, so I can beta test and help with figuring out what is needed to make it work and UX stuff etc.

I did manage to somewhat decompile the TDS700D FAS using 'IDA Pro Free', and bumbled through the process to export it to a HTML file so I could scan through it to find the test equipment that appears to be supported via GPIB.
A bunch of the listed gear doesn't meet the specs required to calibrate the TDS scopes, so I think there may be a bit of reused code, which stands to reason. Why reinvent the wheel for each scope when you have code that works?
If this is the case, it would mean that it should be easier to support more scopes as the duplicated code only needs to be replicated once.
It would be fantastic if USB-GPIB adapters could be supported (I have the Keysight one) and it can be run in Win 10 with nice verbose diagnostic and error reporting if anything goes wrong.
Having the possibility for semi-auto and auto adjustment as per the original would make things much easier too.
If the GPIB devices used for auto/semi-auto adjustment could be defined with plug-in files, that would make adding newer equipment and other equipment that is readily available much simpler too.
These instruments listed below appear to be compatible with the Tek TDS scope Field Adjustment Software.
The TDS700D .exe file was decompiled to discover this list, and other FAS packages haven't been checked, but the list should be similar.
* Possible allowable categories for entries in 'g-config' file
Dc Dm Osc Sc Cg Pm Sa Sm Atten Cal Fg Ps Sg Rt
* Categories with listed instruments (items without a description are currently unknown)
-Oa
oa5002 : Tek OA5002 1100 to 1600nm singlemode fiber optic attentuator TM5000
oa5012 : Tek OA5012 750 to 1600nm 50um multimode fiber optic attentuator TM5000
oa5022 : Tek OA5022 750 to 1600nm 62.5um multimode fiber optic attentuator TM5000
-Atten (Attenuator)
Tm1095 : Tek 067-1095-99 attenuator TM5000
At5010 : Tek AT5010 50ohm 18GHz programmable attentuator TM5000
At3201t : API/Weinshel 50ohm 3GHz attenuator (With programmable controller)
-Cg (Calibration Generator)
cg5001 : Tek CG5001 Programmable calibration generator TM5000
cg5010 : Tek CG5010 Programmable calibration generator TM5000
cg5011 : Tek CG5011 Programmable calibration generator TM5000
-Dc (Digital Counter)
dc5010 : Tek DC5010 350MHz programmable frequency counter TM5000
dc2465
hp53131a : HP 53131a 225MHz Universal Frequency Counter/Timer
-Pg (Pulse Gen)
wt9500 : WaveTek/Fluke 9500 calibrator
-Ps (Power Supply)
dp8200 : Data Precision 8200 DC volt/current standard
dw4800
fl5100b : Fluke 5100B calibrator
fl5700a : Fluke 5700A multifunction calibrator
ps5004 : Programmable precision DC power supply TM5000
ps5010 : Tek Programmable triple DC power supply TM5000
wt9100f : WaveTek/Fluke 9100 calibrator
wt9100r : WaveTek/Fluke 9100 calibrator
wt9500 : WaveTek/Fluke 9500 calibrator
-Rt
gp700 : Dicon fiber optic switch
hp3488a : HP Switch control unit
rd1200
rd1264
si5020 : Tek DC - 18 GHz microwave switcher TM5000
tsi8150 : Tek Relay driver card mainframe
wt9500 : WaveTek/Fluke 9500 calibrator
vx5020
-Sg (Sinewave Generator)
aps1
aps1b
sp5030
fg5010 : Tek 20MHz signal generator TM5000
fl606 : Fluke 105GHz RF Generator (fluke 6060?)
fl5200a : Fluke programmable AC Calibrator
hp8642a : HP 100kHz to 1050MHz signal generator
hp8656a : HP 100kHz to 990MHz synthesized signal generator
hpesg : HP ESG-series analog RF signal generator
mi2024 : Marconi 2024 9kHz to 2.4GHz synthesized signal generator
sg503 : Tek Leveled sine wave generator TM500 (No GPIB control)
sg504 : Tek Leveled sine wave generator TM500 (No GPIB control)
sg5010 : Tek audio signal generator TM5000
sg5030 : Tek Leveled sine wave generator TM5000
smt03 : Rohde & Schwarz 5kHz to 3GHz RF generator
wt6645b40 : Wiltron 10Mhz to 18GHz 6645 synthesized signal generator
wt6722a20 : Wiltron 10MHz to 12.4GHz 6722 synthesized signal generator
wt6747a20 : Wiltron 10Mhz to 18GHz 6747 synthesized signal generator
wt6759b10 : Wiltron 10Mhz to 26.5GHz 6759 synthesized signal generator
wt6769b2u : Wiltron 10Mhz to 40GHz 6769 synthesized signal generator
wt9100r : WaveTek/Fluke 9100 calibrator
wt9500 : WaveTek/Fluke 9500 calibrator
-Dm (Digital Multimeter)
dm2000
dm2465
dm5010 : Tek 4.5 digit multimeter TM5000
dm5110 : Tek 4.5 digit multimeter TM5000
dm5120 : Tek 6.5 digit multimeter TM5000
fl8840a : Fluke 8840A 5.5 digit multimeter
fl8842a : Fluke 8842A 5.5 digit multimeter
hp3456a : HP 3456a 6.5 digit multimeter
hp3457a : HP 3457a 7.5 digit multimeter
hp3478a : HP 3457a 5.5 digit multimeter
-Fg (Function Generator)
fg5010 : Tek 20MHz signal generator TM5000
hp3325a : HP 20MHz function generator
hp8116a : HP 50MHz 8116A pulse/function generator
wt9100r : WaveTek/Fluke 9100 calibrator
wt9500 : WaveTek/Fluke 9500 calibrator
----------
Additional instruments mentioned in .exe, maybe only for on-production line diagnostics and troubleshooting or maybe not implemented???
Sa
hp3585a
hp6627a
Sc
scalcf1
Pm
ma6960
hu47770h
hp436a
hp437b
nrvs
hp60500
Sw.Sm.Osc
osc2465
mi5010
Maybe we should start a new thread for this and see what we can figure out?
[EDIT]
The current list of TDS scopes I have:
TDS210
TDS220
TDS620B
TDS644A
TDS680B
TDS714L
TDS754D (x2)
TDS784C
TDS784D
TDS794D