Here's an example: https://parkercs.tech/enabling-802-11r-fast-roaming-transiti...
I did lose the central management interface of Mikrotik (CAPsMAN) but for my home set-up this wasn't a big deal. I used the backup and restore capability in OpenWRT's LUCI interface to clone most of the settings.
Roaming / fast transition now works much better. I do still lose a few packets as I wonder around but nowhere near as flakey as on the Mikrotik stack.
I did spend an inordinate amount of time optimising channels, signal strength and placement etc. on the Mikrotik stack before migrating over, and so I kept these settings on OpenWRT. I think a lot of making wifi work well is in this particular black art. All things being equal, though, OpenWRT works better for me.
That has been my (one?) major complaint with my Ubiquiti APs - I have four of them scattered around my house/garage and moving between them always suffers a bit of a delay in handing over (or refusing to hand over at all).
I recently migrated a router (not Ubiquiti) over to OpenWRT and have been happy with the stability. I read a bit about roaming, but thought it looked a little daunting.