The term for the tube with a closed end is call a "thermowell". Normally they are stainless. The ones for brewing can be very long, 30cm. You can pick up all sorts of them from aliexpress.
Then, as BennoG says, I'd stuff a bunch of probes down them. Personally I'd much prefer proper 3 wire pt100 probes, you can also get them from "funny bunny"'s store.
He has the ones without covers, they are pretty easy to work with mechanically as the junction is only a mm or so. That would be very easy to wire and stuff.
This said, the normal MAX31865 is an spi device and you only get one probe per chip. (I have good multiple board esp-idf drivers if you go this way and want them).
Your other option, DS18B20 would be much easier, they can all be run straight to your MCU with no driver board, they are quite precise. With .5 degrees of a PT100 based on my experience using them quite a bit. (They need pullups btw). The biggest down side would be getting a lot of them in a thermo well.
ps, 0.1 is quite easy for the pt100. That's why I aim for.
I also have a pt100 on a bonded teflon tube. You could just fix these together and pull them apart for cleaning. Food safe, acid safe to the max. Not safe amongst forever chemical fear-mongers, unless you want top go past 550.