I must say that this took a long time coming from a service that prioritize user privacy... but it's finally here. After an online petition with over 1000 signatures, the general manager (David peterson) has announced that XMR will be added to ProtonVPN before the end of the summer:
https://x.com/davidgpeterson/status/1941500514803548636This does not include their other services (such as ProtonMail) given that it's another team handling it but it's a good start I would say.