RockShox you can generally get away with servicing yourself. I haven’t done a charger damper yet, but I think the only special tool it requires a bench vice. Their air shock required a $12 adapter that to “charge” the damper, and a pipe strap to get the air can off. Dunbar had the adapter in stock and other shops were able to get it for me so it’s not totally uncommon.
There’s a manual for all of Rockshoxs products and dampers that I’ve generally found easy to follow. Take a look for your fork/shock and see if it’s worth doing for you.
I am not a pro and I have had the whole damper or airspring spin in the lowers instead of allowing me to unthread the foot bolt. Definitely use a torque wrench when doing things back up and use lock-tite where it says to.
Fox and Xfusion typically use a nitrogen charge port, but there’s a guy on mtbr that screwed in a fuel rail bleed port off of an old ford V8 engine that allowed him to charge a fox shock with a regular air shock. Fox lists the pressures for nitrogen, which I assume would be the same for air. Xfusion is a guess based on similar fox and RockShox pressures. Probably just send those shocks off for service.
Taking anything apart that’s pressurized is dangerous. Make sure you release all the pressure in a shock or fork before you begin to disassemble it.