Yes, and its super hard now. When I installed the new android version the only way I could get fdroid installed was flashing it as a system app in the recovery.
You have to do that on Windows and macOS now as well...
I haven't had to enable some global setting to allow unknown programs on Windows 10. What are you referring to?
Last time I did a fresh install of Windows 10 Home I had to go into Apps & features and disable "Allow apps from the Store only" in order to install Chrome. Didn't seem to have to do that on Windows 10 Pro.