The issue I mentioned before will be a challenge. Since there are no mounting holes on the PCB and it's covered in traces to the very edge, there isn't really an easy way to create a cover that can securely connected to the PCB. Friction fit wouldn't work since it may damage the PCB over time/use and expose traces, and the only other way I can think of is to secure the housing to the wiring instead. That also isn't ideal since you'd be tugging on the wiring, and by extension the solder joints, every time you remove the PCB from the slot.
One rather inconvenient way to a solution is to recreate the PCB yourself in CAD and have it fabricated with someone like JLCPCB. That way you can have mounting holes included, and a cover can be easily made. It's a lot of work for just a cover though...