@naizena If you can the best way at present would be imho to use the installer use the wipe and bootstrap option to get a clean install of just 20.04.
If, as I think you did and try RC you will still keep all your 16.04 apps. Some if which will still work others will not. TELEports does work but you need to install the 20.04 version from the 20.04 version of the OpenStore now on your device. When you go back to 16.04 you may have to do the same again. The process is not the same as changing channels in 16.04 you are in affect changing OS.
I know they are not in the Focal OPenStore but can anyone confirm if 2FA Manager or Aiuthenticator NG work on 20.04. Sure i read somewhere that one of then does think is was Authenticator NG
EDIT: Yes they do
@mrt10001 Further update, the phone won't power off, so it has to be a hard switch off. I have gone back to 16.04 to compare some things. With 20.04 it was difficult to get to the bootloader on this particular phone.
@messayisto Despite of this I have to say how amazingly quick the development is going at the moment! With every days version new features are working - thats so great! thank you all.