If it ever interests you: https://nextdns.io/?from=d6jchbnv (my affiliate link).
I am pretty active in the blocklist community, co-maintain a FOSS network monitor and firewall for Android, was a contributor to AOSP, and run a public DoH/DoT resolver; to me, the writing has been on the wall for the past few years. Plugins like uBlockOrigin, alt web-based front-ends like Invidious, and reverse-engineered apps like YouTube ReVanced will most likely be the only options left in the not so distant future.
It also doesn’t always work, particularly if the app isn’t covered in your blocklist (which it isn’t always possible to add them in any easy way, because “think different”)/the app hosts ad content directly.
If you really do refuse to use apps with promoted content then I guess you don't install anything to your iPhone.
The App Store is such a shit show now, I only go there when someone links to an interesting app from a website or podcast notes.
Now, if Apple unlocked the bootloader and promised no more ownership shenanigans, I'd never badmouth Tim or his company's software ever again. This website has my word on that.
To a first approximation, no one cares about open source app stores on Android.
Epic tried to bypass the Play Store and it was a disaster for them.