I am not sure.
I managed to implement a rejoin-like functionality. It allows a player to attempt to rejoin the lobby after X seconds when the lobby did not manage to connect to all peers. It is similar to a player rejoining a custom lobby. See also #6479.
However, I noticed that the lobby implementation is brittle. The rejoin tends to fail by... crashing the game. And I'm not doing anything special there - when I exit the lobby it occasionally crashes. Maybe that is because I run multiple instances on the same machine, I do not know. At the moment it is disabled.
If we do want to take this road then I feel we need much more statistics. Grafana (a tool to see how many lobbies there are, etc) recently got back up with thanks to Sheikah and Brutus. We'd need to expand that to track other lobby-related statistics . One of them is the local status of a player. And when a player attempts to rejoin. And whether that succeeded.