Yes. Apps can be installed from anywhere if you go into your settings and allow apps to be installed from external locations. It's really easy and is standard practice. Always has been. So, install your F-Droid store or just go to GitHub, whenever. Just make sure you know what you're installing. You don't want to get malware.
Discussion
I'm sure the apps developed by you for Android, definitely won't contain any "unwanted" code 😁😁 But you are right, I forgot to mention that be careful. Om the other hand many of the alternative Android app stores examine the uploaded apps before it will be public (unfortunately the Aptoide is not so secure: it always want to get "root" rights/privileges, I don't know why...)