For myself, I use a static IP on all peripheral devices, like printers and scanners, in combination with a whitelist on the router because my devices don’t change very often and I can add new ones individually as they are acquired. Works well, and freely allows home network use while blocking external network access.

Beware any built-in home router solution like “parental block” for isolating devices because on mine at least, it only blocks IPv4 and anything using IPv6 sails right past it.

Also, you probably already do this, but always test, and keep a backup of your router/whitelist/exception settings.