Firewalla blue for parental controls

I stupidly purchased a Firewalla Blue second hand because it's hard to get Firewalla in the Uk.

Was obviously scammed as it's already at the EOL.

I only want to use it for parental controls (to monitor and block teenage devices) and nothing more but saw that even the App will no longer work.

Is there any way to still get it to work for that function only? Thanks!