Parental control filtering
I'm using Proton VPN at the router level. It would be very interesting being able to customize downloaded VPN protocols to block certain type of websites or even specific classic websites or apps, like YouTube, Facebook, BeReal, nudity, violence etc. Yes it can be done on the router but if the VPN was providing such DNS filtering it could be more efficient.
Guillaume shared this idea
Similarly, for router level blocking, https://protonmail.uservoice.com/forums/932836-proton-vpn/suggestions/46313413-provide-netshield-option-for-parental-content-filt