UVC is the absolute best thing to kill everything. Some sources, cough, cough, will even use it as part of their sterilization process. In the hospital, at the beginning of C N95's were being "recycled" sterilizing them with UVC... After a patient with C leaves a room we use a UVC "robot" that flashes UVC light around the room like a disco ball to disinfect the entire room. DO NOT let UVC light touch your skin, may be carcinogenic and/or damaging to DNA... BUT, it is not perfect, it can still be blocked by glass and many plastics. So, the question to ask is, will the UVC light sterilize where it needs to and where do I need to use soap and water?
Prices may have gone since C but you can find a variety of UVC boxes on ebay at a reasonable price, I bought a couple for my unit so the staff could sterilize their own mask, the ones "just" for CPAP is because of marketing.