Earlier quoted context omitted.
For people that are not aware: There's a Telegram FOSS [1] fork which contains all kinds of fixes; and additionally is Google Services and tracking free, which means it will run on AOSP and LineageOS without any burden of push services. You can verify this yourself with AppWarden [2]. [1] https://github.com/Telegram-FOSS-Team/Telegram-FOSS [2] https://gitlab.com/AuroraOSS/AppWarden
being FOSS just in the client side, IMO changes little in comparsion with WhatsApp.
There are efforts implementing mtproto servers that are compatible with the Telegram codebase like telegramd [1] or madelineproto [2] in case you want to host your own server.
But, if decentralization is your main focus (interpreting your statement); you probably want to switch to a Matrix-based client anyways.