Why don't you just download from here https://www.thunderbird.net/en-US/thunderbird/beta/all/, extract and run? It doesn't get easier than that. This was already mentioned in the replies of the thread you linked to.

See also Install Thunderbird on Linux and Thunderbird Beta

I know this is tar package. But, for the further update I need to remove reinstall it manually which is quite impractical for longer term.

See https://snapcraft.io/thunderbird

Found it here https://askubuntu.com/questions/1270573/cannot-upgrade-to-latest-version-of-thunderbird-78

ok, snap package looks good and is there any flatpak as well?

ok, snap package looks good and is there any flatpak as well?

I don't know. You'll have to find that out for yourself. Try Googling for it.