I would like to be able to create new zones and assign VLAN interfaces to zones other than LAN or WAN.
Just to get the hang of it. Is this the same as the already existing color concept or is it some more extended version of it. How would it work and be used?
VLANs are assigned to zones, then rulesets are applied to zone pairs (e.g. WAN → Servers, Servers → Printers)
So, it would simplify firewall rules handling. 
There should also be a LOCAL zone, for packets destined for the router itself (e.g. different rules for LAN->LOCAL, Servers->Local, WAN->Local.
bumping this because I do, love the way that ubiquiti implements ZBF, would be cool to implement it in the GUI. very few firewall vendors have ZBF!
You could essentially do this with Firewall Groups. . I think the ask here is more for a simplified GUI with red and green to show where traffic is going? The Ubiquiti deal seems neat but I would think that in larger networks it might start to lose value. What Alta is doing is in line with traditional firewalls and how they handle Firewall groups gives a pretty powerful way to simplify your rule base.