Cisco's mobility express just runs on one of the APs and can fail over to another of the APs; it's a slick piece of software.
And yes, it isn't open source, which is a real shame since cisco's killed it (as far as I can tell) and it probably represents an enormous and sophisticated investment in effort and engineering and it'll just melt into entropy.
I loath cisco and don't recommend their kit lightly. In this one case, they seem to have accidentally made (for my use case, running 5 APs at home) a perfect product. They're cheap, extremely reliable, my wife doesn't hate them (though mostly they're in the attic or basement; only one is visible), they've got a (relatively) easy to use UI that manages all of them at once, and (Except for the switch 2) they seem to just work even though I've got vlans and lots of SSIDs and other goofy stuff).
If I had a simpler house to support, I'd just get a single WRT capable "big fast" router / AP...
I'll put in an ebay search notification for when the R650 (and R750) for $50 each and maybe it'll ding in a couple years and I'll be in a place to swap out the 3802 network I've got running now...
As far as I can tell, in this one case (with mobility express) it seems like Cisco accidentally did something overall (IMO) "good" for the world by making it possible for their kit to be reused by some part of the world where someone will get utility out of the still very nice equipment and somehow cisco won't see a dime from that "someone is using cisco equipment" event.
Mobility express isn't perfect, but considering the cost of the gear and the cost of the license, it is pretty darned good. I suspect some product manager at cisco got fired for accidentally making the world not quite as bad a place as it could be if cisco extracted license fees on all the 2802, 3802, and 4800 access points or otherwise sent them to the e-waste bin 4 years early.
You have any docs on how to set these up? I believe a firmware change is required.
That said, the cisco firmware for this specific generation of access points is actually free and trivial to get -- create yourself a cisco account and go to downloads and download the 3802 "mobility express" firmware. The last ME firmware came out in 2024 and all this equipment and software is now totally unsupported by cisco so don't run PCI transactions at home... I'd also avoid running their captive portal or some of their other weird features...
Actually setting it up is a bit of a chore but it is a full featured "enterprise" (cough) AP management system with all the knobs and twiddles you could ask for.
It's really only a good idea if you don't value your time (like me) or if you have a sprawling plaster house where you want to have lots of cheap access points instead of a couple super fast ones.
Lastly, for better or worse, I haven't been able to make my kid's switch 2 work on the network.
Uni has an adapter for USB to Ethernet (if wired is an option) that works with those Nintendo devices, I have one that an extended family member borrowed (unknown if the Switch was a 1 or 2).
But in the one specific case of mobility express, you can ... just download it. Unexpected but actually pretty cool.
You still have to figure out installing and configuring it, which is mildly tedious, and you'll probably need one of those cisco serial cables, but it is an exciting side-quest instead of a dirty forum crawl.
To bring it back to "openwrt" -- this nonsense by cisco, broadcom, HP, IBM, etc is why generation after generation the "enterprise" market is dying -- they're excluding 90% of the would-be engineers from the job market protecting their e-waste from secondary or later reuse, likely just on the off-chance they might make a tiny amount of money downstream. But I guess that's not a line-item that shows up in the quarterly reports (what's the value of "community goodwill" ?)