If you want to use UE 4.27 and meta, then I suggest you use this branch: https://github.com/uno1982/UnrealEngine/tree/4.27-plus-meta there's been a lot of improvements made to it to help smooth things out. It also contains setup instructions which should hopefully resolve any issues you're seeing. The person who helped author that branch has a discord where you could get some specific help if needed: https://discord.gg/a9RTgQtCqn
I don't know how much this will matter, but if you're looking to package for Quest, the way we've always done it is the through the Package option instead of the launch option. So, File->PackageProject->Android->Android(ASTC). Then take the .apk it gives you (Make sure in ProjectSettings->Platforms->Android that Package game data inside .apk? is true) and put that .apk directly on your headset via Meta Quest Developer Hub.
if you want to play test via UE, just make sure the Quest is set as your OpenXR default (done via Meta Quest Link->Settings->General) and that you have developer mode enabled (Meta Quest Link->Settings->Beta). Doing that, should allow you to utilzie VR Preview in the UE editor.
I hope this helps! Feel free to reach out again here or on Discord(s) if you're still having a hard time!