Lounge / studio partition door / soundproofing advice

It is not going to be easy to get the best of both worlds.

Part of this depends upon the amount of acoustic isolation you desire/need between lounge and studio?
For best acoustic purposes aim for heavyweight doors that are well sealed otherwise higher frequencies can be well attenuated and lower ones not. Entrances to studios are often double 'air lock' types. I doubt if you can achieve good isolation with bifold ones unless they are heavyweight.

You might get away with that sort of arrangement if you do not need high levels of isolation and you could always add an acoustic curtain (again of heavy material).

You might need to decide how much isolation is required relative to isolation from the environment in the world outside your garage.

If you are considering the isolation to be an issue (your reason for the question?) then perhaps you also need to consider the suitability of the garage as a studio. If it has parallel plain flat walls, concrete flat floor and the like you really should consider adding acoustic materials to modify and break up those audio reflections that will result from things like standing waves.

It all depends on the quality you wish to achieve and the 'sound' of and limitations of your studio!