What's the multi-VLAN recommended configuration?

What’s the multi-VLAN configuration recommendation around here? The idea is isolate as many/all IoT devices to a separate VLAN which has no Internet connection, and then also have Home-Assistant be able to talk on that VLAN, while also being part of the general VLAN which, for example, my phone is on so I can manage/monitor it directly. And it also has Internet access, for updates, pulling add-ons, updated weather, etc.

Is it recommended to multi-home on both VLANs with 2 ethernet connections? Or specifically route between them? If routed, how to handle broadcasts/mDNS/etc so that things auto-discover themselves properly, along with HA?

Ive gone the multi-VLAN approach, as I found the routing of broadcast discovery too much of a pain. mdns was OK as my router has a mdns repeater built in.

I’ve got a green (internal) and orange (iot) vlan in HA, and it access the internet out through the green interface. That was pretty easy to do using the core (venv) HA install, just installed the 802.1q package into Raspbian and then setup a trunk to the switch.