I think it's safe to assume that Brume 1 won't be getting official v 4.x firmware due to being EOL. Still use it as my only router though (+ AP's for WiFi), but wondering if the latest beta version does support ZeroTier (or Tailscale?)
I do have a Brume 2 readily available to replace it when the time comes, but have no problems in keeping the MV1000 for the time being.