> As far as I can tell, the only implementations for the platforms I care about are the “official” ones
Telethon (https://github.com/LonamiWebs/Telethon) is a decent up to date (with MTProto) independent clean-room client implementation in the form of a Python lib.
You might consider trying to take care about it.
I mean, I could, but the Telegram developers being so opaque about this doesn’t make me feel like this is a good use of my time.
> There are many implementations already.
As far as I can tell, the only implementations for the platforms I care about are the “official” ones (in the sense that they are placed under some random person’s GitHub account and linked to by the Telegram website).
> You can also compile the official client yourself.
I have never been able to get this to work. Either way, what I compile from the “sources” they have put online and what they are shipping are two different things.