Some apps include Google libraries in their PlayStore version. One infamous example is Calculator++. Telegram is also like that.
You'd have to actively look up which app varies in its Play/github versions, and such info may not always be available.
Instead you can use F-Droid, which is understandably not recommended but still very convenient.
Alternatively, use Obtainium, you have to manually input each app & its github link, but once you set it up, it's smooth sailing.