The developers of every one of those applications you mentioned had plenty of time to update their apps for Big Sur. They are lazy developers and I find it so odd that people support lazy developers. If a developer of an application (especially something not considered a major commercially-released product like Thunderbird or Libre Office) takes their sweet time then I'm jumping ship on them.
First and foremost, a number of developers take the understandable, wise choice of waiting until the initial version of the mac OS is released. Given that (and usually the next one, ie. .1) the initial release has bugs, the developers want to get it right.
Secondly, as I've said many times, the first couple of versions of any mac OS have too many bugs, and thus another reason to avoid it.
Third, I see nothing "earth shattering", nor anything in Big Sur, that compels me to upgrade right away. Hence, really no need to rush.
Fourth, regarding SuperDuper! (SD), here is what Dave Nanian (developer of SuperDuper!) communicated to me when I asked him about the issue:
"We are forced to use asr (not ssr) to make a bootable copy, and since it doesn't work yet, we haven't been able to test with it, other than to prove it doesn't work.
I do not know when Apple will fix their tool. We've been asking all summer."
From another Mac discussion site I am on, Bombich Software (developers of Carbon Copy Cloner (CCC)) is having similar issues.
So, neither of them are lazy. I do find it strange that some folks take such a view (laziness) without knowing the facts, nor history. Reminds me of fake news.
Finally, developers of such products as SuperDuper!, Carbon Copy Cloner, Onyx, and Tech Tool Pro are dealing with complex disk "level" issues, and as such, are taking extra care to get it right. Plus, Apple has been known to 1) make it difficult for such developers, and 2) make last minute changes that affect such software. Look at what they did when OS 10.15.5 was released. Definitely caused serious issues with SD and CCC. Fortunately, Apple realized their mistake, and corrected the issue in OS 10.15.6 (and it's OK in V10.15.7).
So, to sum up, I have no problem in waiting until all my third party applications are compatible. The developers are doing the right thing. Meanwhile, I am fine with Catalina, as it is stable, and works fine. If some folks want to take the plunge, and still have third party software that is not yet compatible, be my guest. I can wait on the sidelines and learn some things about Big Sur, all without causing me issues/problems.