Hey, thank you so much, my issue is now solved!
I was trying to open the .apk package with Amaze, an Android file manager.
Since I opened it with the native /e/ file manager, it just installed without any problem.
If Amaze is not working as it should, take a look at their GitHub to see if that is a known issue.
Did a quick check myself and didn’t see anything other than a whole lot of crash reports.
EDIT: Just installed Amaze on /e/. It works as expected when tapping on an apk file.