I've decided that I'm now too old for knitting my own routers from shell scripts.
There must be something that Just Works and can cope with IPv6, a couple of WAN interfaces and an assortment of local VLANs with various firewalls between them.
I got to that point a Several of years ago.
So I just Paid The Man (Rev RAK) for a Firebrick, and let it get on with it.
It's a small single-box thing, and really very configurable.
And I just accept that I may need to adjust my requirements to suit, if I can't configure it exactly how I want.
I've not had to do that, and I've got a fairly non-domestic configuration here.
(And I'm tunnelling my AAISP IP addresses over Starlink for added fun, using AAISP's L2TP facility.
Yay! I pay for 2 ISPs.)
Also it consumes much less power than the small PC stuffed with NICs that it replaced.
Regarding the MicroTik kit, on the AAISP IRC channel, you will often pick up some noise about people knitting their own using the MicroTik routerboard devices, but I've never explored that. I'm at the CBA stage with that.