You have the option to get a solid hardware that you can install openwrt on, and then use the Deco mesh just for the Wifi. That'll give you similar, if not the same results, and save you a few bucks in the process.
I just started migrating my network from PFSense, a bunch of tplink switches and Aruba InstantOn APs to unifi. I'm almost done (just missing a couple of APs more and 1 more switch), and I honestly am extremely happy with the decision. The Unifi APs are not as powerful as the Arubas, but the improvements to the performance of my network more than makes up for that.
I apologize. I misunderstood that you were looking for a mesh system that would work with an existing openwrt router. Seems what you're looking for is a mesh system that can be flashed with openwrt.
For that I can only suggest that you look at the supported hardware table and see if you can find what you need.
I was just going to say. I have 2 LG TVs at home, not the official SD dock, but a couple of aftermarket ones, and they both work perfectly fine.
Also, LG TVs are notoriously slow to display after a change of HDMI (1 to 2 for example), so make sure you give it a few seconds (both my TVs can take up to 10 seconds to display).
I've only had it for about 4 months, but no annoyances so far. It did crash once, and it takes (in my opinion) ridiculous amounts of time to fail over a Vlan when one of my Lans goes down (upwards of 5 minutes, when my PFSense was almost instant), but other than that, it's been super solid.
With the current browsers panorama, it's important to use more than 1 browser. My main browser is Librewolf, then Brave for work, and Mullvad for all the rest. The reason being that almost every site is made to work first on Chrome and everything else is an afterthought (so I use Brave for those).
I'm in the (long) process of migrating a mix of PFsense + Tplink switches + Aruba Instant On APs to a fully unifi infrastructure. Even with the mix of devices, my network has been way more solid than ever with a Unifi Gateway Ultra, a few NanoHD APs (still mixed with some Arubas) and 1 unifi switch assisted by the rest of the tplinks.
I should finish the migration next week, no regrets.
The level and ease of control I have now would not have been possible with the previous infrastructure.
If you can still return the Omada devices, I suggest you do and go Unifi.
I got a brand called JSAUX. In my case I pickles 2 of the 6-in-1 because of all the USB-A ports, but they have different sizes.
This is the one I purchased:
https://www.amazon.com/JSAUX-Compatible-Ethernet-Charging-Deck-HB0603/dp/B0B7HVZNMB