Is there really much difference between Big Sur and Catalina? Having already gone through the pain caused (to me) by Catalina, I doubt that Big Sur will create similar additional problems, but I might be wrong. In what ways is Big Sur incredible?
Existing users who haven't migrated past Mojave might want to think very carefully before "upgrading" either to Catalina or Big Sur. You have been warned!
A lot of the Catalina "problems" come from the elimination of 32 bit software, though that might not be the only reason that some things are difficult. Another reason might be the "checks" which Apple make for software which has not been bought through their App Store. I gather that they charge vendors around 30% for such approval. While it's good to know that software "might" be guaranteed to work and have no obvious vulnerabilities, it seems odd that some software add-ons which have seemingly worked find in earlier versions now do not work at all, because they don't meet with Apple's approval. This smacks of a racket. It affects products such as Logic Pro X.
Apple don't always help existing users - though as commented above, their hardware services are rather good. I rather resent what may be an accidental (but I'm giving them the benefit of the doubt .....) approach to software updates. I installed a recent version of Logic Pro X, then Catalina - which caused me no end of bother - and then Apple released an update to the version of Logic Pro X which I'd barely installed, yet it won't even run (or so Apple claim - so won't install) on the version of Catalina I have installed. What are they playing at?
I wouldn't expect people who are new to Apple to have big problems, as presumably most of the software they'll use will be matched to their machine(s) and operating systems. Issues will probably arise later, due to updates and incompatibilities.
Re the external Touchbar idea - I guess it would only really make sense in an external keyboard, rather than yet another device. It might be useful, though, although I have no experience of computers with such touchbars.