After a little more research and picking the brain of one of fellow mentors, @johnbishop, who has first hand knowledge of CPAP machines, I found that there are some very effective CPAP cleaners on the market that will sanitize the machines/parts with a high degree of efficacy in killing and preventing growth of bacteria.
One product called SoClean seems to be the front runner in the business.
https://www.soclean.com/soclean3/product-category/sale
It uses ultraviolet light to kill the bacteria on all surfaces, assuring clean and germ free breathing. This is the same process used at Mayo with their sanitizing Robot who comes into rooms after a patient is discharged. It disinfects the entire room with the ultraviolet light.
There is also a conversation on the Connect forum you might find of interest. -- What is your CPAP Cleaning Routine?: https://connect.mayoclinic.org/discussion/cpap-cleaning-routine/

When your husband has his pre-transplant educational classes he will (you both will, as his caregiver) have a lot of information tossed your way for avoiding infections.
Cleveland Clinic, another reputable transplant clinic, has really good information online on prevention-post transplant. While it doesn’t specifically cover CPAP machines it gives a comprehensive guide to staying safe, what to avoid such as room humidifiers, and common things we might overlook. Where I stayed for my 100+ days, the first thing I ask housekeeping for was a new shower curtain liner in my bathroom. They were great in accommodating my request.
https://my.clevelandclinic.org/health/diseases/4511-bone-marrow-transplant-preventing-infections
Have you looked into one of the disinfecting machines for your husbands CPAP?