F-Droid is an alternate app store, having mostly open source stuff on it.
It's amazing the speed difference in apps from F-Droid versus the official google Play Store.
I recently had to get a new phone, the old phone's battery was dying. Android does a great job of copying old phone data to the new phone, but nothing from F-Droid copied over. All the open source stuff was deemed dangerous by Google.
So +1 for F-Droid!!
Apps from F-Droid that I use regularly are:
RiMusic - Youtube Music player that you can shut off the screen and just listen to music, without ads.
NewPipe - Youtube player that isn't youtube, so no ads or other bloaty BS.
droidVNC - Fantastic app that lets me control my phone via VNC. Similar in functionality to scrcpy, but works all the time. Phone doesn't have to be rooted for it to work.
Material Files - Not just a file browser, but the bit I use the most is the FTP server that is built in. I use that every day to do a system backup of my work files to my phone. Very convenient.
Breezy Weather - A simple, quick weather app. If you're Australian and use the official Bureau of Meteorology app on an old phone, you'll know how painfully slow it is. Breezy is not slow at all.