After I posted my comment I found this https://protonvpn.com/support/linux-prerelease/
To reply to your comment: they do send out emails regarding product development occasionally but there's no publicly available "roadmap". I can understand why as development times are hard to predict, so I don't fault them for that.
I can say that even though they are majorly updating things every week, they do make constant progress and release new products. I've been a subscriber for years, back when it was only "ProtonMail".
Now we have Proton Mail, VPN, Calendar, Drive, and Proton Pass. I'm glad my money has been supporting the vision and development of all these great privacy-first services. For me that's why I have been a loyal customer all these years.
Oh you're talking about AdGuard VPN not solely the main AdGuard product. Definitely not ideal. It doesn't offer the same level of features as my current VPN who offers ad blocking anyway. Not to mention a few suspicious quotes from their website:
Considering Cyprus telecommunications laws it doesn't seem like the safest place to headquarter a telecommunications privacy company.