It would not be nice to play all sports matches except tennis competitions without an audience. It is the audience that makes the matches beautiful.
Really, would you watch a Liverpool match without listening to the You'll Never Walk Alone anthem?
That's the part of the new normal. Having a live audience can't just be pushed easily.
For the sake of resuming some leagues, expect that it will be different compare to normal.
After all, the usual live audience ambiance will go back soon once everything is now ok. So better start it slowly.
Billiards don't need a lot of people in a match and the game can be relaxed and keep a distance of 1 or 2 meters if there are committees, opponents playing etc.,
Aside from that, billiards are known to have a calm atmosphere like there is no one watching.
Same with CHESS so I will add this to the list. Literally no need for an audience for this game.