steve66th I believe Obtanium works well with AppVerifier, you can share from Obtanium straight to it before installation, if I'm not mistaken.
I am not sure if the devs of AppVerifier are concentrating their efforts on adding every single app to the internal database and keeping that updated (not that the hashes change that often but it does happen occasionally), I may be wrong though.
You can obtain the hashes for apps from other places too, like from the developer or from a friend who has the app installed already, or even from this forum. I would be happy to give you the SHA-256 hashes of any app that you want to install, if I already have it installed. Though I don't think it would be appropriate to do that in this thread as that is pretty far off-topic from OP's original question.
Out of interest though, would you mind explaining what you meant about apps running with containers and wondering how a VPN app could work? Not sure what you meant there. Sounds like you're used to how desktop OSes run. If you want a terminal app, there are some options, with the closest to a desktop experience being Termux, though there are some very big security issues with that one so I wouldn't recommend it unfortunately. I know there are others, but I'm not sure which is the best in terms of security.