F-Droid is an installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform. The client makes it easy to browse, install, and keep track of updates on your device.
(1) You can install F-droid app: it acts as a "Play Store" to install these FOSS in their catalog; or
(2) search FOSS app in their site, manually download and install the apk file yourself.
No trying to hijack this post, but I'll post an f-droid based Telegram app link (for android), you may give it a try:
Telegram FOSS
What is f-android. Learn me plz
https://f-droid.org/en/
(1) You can install F-droid app: it acts as a "Play Store" to install these FOSS in their catalog; or
(2) search FOSS app in their site, manually download and install the apk file yourself.
so its an alt app store?
Yes in a way, but FOSS apps (no mainstream apps) for Android.
What I can call an alternative "Play store" is this:
Aurora Store