If you really have a high frequency application, do you need all the 'gee whiz' measurements, channels and decoding? Not at all!
So, what's wrong with having a fully featured DSO with all the modern features that has a realistic bandwidth and then some old analog scope for the higher frequencies?
I have an older 350 MHz Tek 485 I picked up for a couple of hundred dollars. It works great and I have been using it for 12 years or so. It doesn't have any of the modern DSO features but it will display higher frequencies just fine. Not that I ever need to, my projects work at 100 MHz or lower, usually much lower.
I bought the DS1054Z for the features, not the bandwidth. Sure, I would love to have a 500 MHz Keysight DSO (or, better, MSO) but this is just a hobby, one of many hobbies, and the money simply isn't there.
Plant a stake in the ground, money wise, and then shop around. The closest thing to the DS1054Z will cost at least twice as much, if not 3 times. Even then, it's still an entry level scope, suitable for student lab projects. Expect to pay > $10k for anything that is engineering lab quality. Even then, it's kind of low level. There are scopes will over $100k and I have never seen one or even been in a building that had one.
It's worth remembering that, if you want to display square waves that are actually square looking, you need a bandwidth several times higher than the base frequency. The 3rd harmonic won't be enough and likely the 5th won't cut it either. So, maybe you need to include the 7th harmonic and now your 100 MHz scope can only display a 13 MHz square wave with any kind of accuracy.
Everything has limitations, there are tradeoffs...