The settings page didn't allow you to manually add hosts if you are on Firefox ESR 115. It does now.
Chrome Mask now spoofs some basic Client Hints usage to address the now more commonly occurring sniffs for it. More precisely, it sets the sec-ch-ua, sec-ch-ua-mobile, and sec-ch-ua-platform headers - and it shims the navigator.userAgentData object to include .brands, .mobile, and .platform. This should get users past currently known instances of CH sniffing, and this can be expanded in the future.