I have chosen to go with a Raspberry Pi 4 for my set-up due to the small form factor and am very new to OpenWRT.
I now need to choose wireless APs that I can dot around my house, I have ethernet in each room so would like to utilize this as a backbone rather than a mesh system.
I was going to buy a bunch of TP-Link Decos to act as APs but thought I would consult the vast knowledge on here before I do.
My end goal is to have 1 SSID for all my devices to connect to with multiple APs, what would I need to do to be able to control the SSIDs/radios from OpenWRT instead of having to log on to the APs to control this?
How big an area are you trying to cover with wifi? You may be able to do the same thing with a single AP such as a TP-Link EAP245 or something from Ubiquiti.
It's only a 1100sqft apartment but its solid concrete walls and chunky doors so I did want to have at least 2 APs to avoid any issues.
Am I able to control Ubiquiti or TP-link EAPs from OpenWRT?
nope, but you can reflash them with openwrt.
What do you intend to "control" ? If you setup these in "AP" mode, all routing + DHCP is handled by OpenWRT on Pi 4. I use TP Link Deco X60 in this manner.
You can't. OpenWrt does not provide any kind of wireless controller (as some commercial mesh systems would) - so luci won't give you access to any remote systems (regardless of what firmware they're running). You will have to log into the APs to change the wireless settings (either one of them, in a setup with a wireless controller or what's generally sold as a 'mesh system', or each of them individually to sync up their configuration).