Actually RF shielding paint is very poor. Manufacturers advertise them with "99.5 %" or so, which equates a measly 20 dB. Additionally, correctly applying these is quite difficult, and incorrect application greatly diminishes the shielding. (You also need to cover everything, including ceiling and floor, not just the walls). Even when correctly applied, the attenuation is so weak, a cell phone will still work. Shielded facilities are built differently and are far more expensive than shielding paint.
RF dead chambers are bloody expensive for a reason: you can't emulate them by pasting some paint on a wall.
One of my first jobs was building shielded boxes for a sensitive RF measurement setup. Containing the RF output from something like a laptop is hard. I lined the inside of the boxes with copper beryllium mesh (attached with glue, since nails become little antennas), soldered all the joints to ensure electrical continuity, and put a copper beryllium gasket all around the lid to make sure there was continuity when the box was closed.
If you need continuous use, two rooms. One that acts as an "airlock" with an outer door that is open only when the door to the other room is closed. Battery operated fans and lights used as necessary.
Note that the "inner room" might be as small as a ammo crate depending on your use case.
RF dead chambers are bloody expensive for a reason: you can't emulate them by pasting some paint on a wall.