Before I sold my FC660C, I took it apart and lubed the sliders a few times with trybosis 3204. It was my first time taking apart a keyboard and wasn’t particularly difficult and the stabilizer keys are really just wider regular topre keys. There is a wire, but it’s inside the key instead of over top like cherry. A good set of tweezers is all you need. There’s a good video by Taeha Types about lubing an HHKB which was not all that different. I’d say the most tedious thing about it was just how many screws there are holding the PCB to the plate

A few things to watch out for:

• be careful about the ribbon cable that goes from the main board to the daughter board that has the usb port on it
• try and keep the domes from separating from the PCB. there shouldn’t be any reason to remove them and they’re held in place with some sort of adhesive. I’ve heard if you take them out then it’s a pain getting it all back together.
• if you take the sliders apart you may break some plastic tabs on them, but that’s normal so don’t worry (see any video about lubing topre)

Feel free to reach out if you have any specific questions! :)

Mechmarket might be a good place to check

I haven’t fact checked this at all but apparently lowprokb.ca is working with Kailh on some choc v1 compatible silent switches which could potentially be used in those boards. Not sure when they’ll be available though

typeractive.xyz is great. It’s run by the maker of the nice!nano microcontroller which is one of the defacto standards for wireless splits. They can be built without any soldering if you get the no solder hot swap headers (for the MCU)

Yes, it’s pretty much that simple but you will also need to change your stabs since there are now two keys to stabilize. That means you might have to take pretty much the whole board apart depending on what kind of stabs you have. It will likely be 2 × 2u stabs