The other way is to use fdroid as source within obtainium. The benefit is to maintain app list at one place, so you can export/import to another device, when needed.

https://apps.obtainium.imranr.dev/ has plenty of apps that don't have F-Droid releases. Many of them come from the developers own website.

And if you see anything is missing, you can always add it!

You can use it with non-github releases too, but it's super rare when one isn't available. In the case when Obtanium doesn't work, I just use F-Droid.