Hmmm...
I believe, it would be more productive to ask something more specific — namely, what do you what to achieve.
Lets say I would like to see if my question was asked and solved cannot as it is at
Many communities get locked behind it and I cannot access anything.
Locked behind what? If you have not access to a certain ‘community’ (i. e.
resource), how do you expect a third-party useragent to help you with that?
just like nitter or bibliogram.
As for (b), many various SaaSʼes exist out there, including some Telegram-related, but I found it inappropriate to advertise them here.
Then do not type here!
As for (a), I have never heard of one, and I am not surprised of that for the following reason. https://twitter.com is a modern ‘webapp’ written in a clean client-server manner, so writing Nitter was a task of writing alternative frontend for undocumented yet pretty stable API. While https://t.me is implemented in a more old-school fashion (it is rather akin to https://mobile.twitter.com), which on the one hand makes it perfectly usable without running ad-hoc javascripts in your browser, but on the other hand makes writing a client for it an unpleasant task, that requires parsing an output for humans.
There is quite a few free clients for non-anonymous Telegram interface, though, including the official one.