I mean you wont really lose muscle in only 2-3 weeks, just glycogen/water which comes back right away so dont worry too much lol.
Just look up more advanced calisthenics, handstands, handstand pushups, planche, pistol squat, shrimp squat, things like that. Same on the pullup up bar, levering, muscle ups, etc
Do some plyos or explosive push ups too. Honestly I get a bit leaner without lifting for short periods bc I am not eating as much and am not bloated lol from stuffing down food. Its also good to take a break 2-3 weeks of just calisthenics youll come back refreshed and stronger, I think calisthenics make people look better too.