Am i missing anything? What brand of router should i get (belkin, linksys, tp-link, xiaomi....)? Does openwrt install inside of another OS or is it the OS? If it is the OS would that mean i cant load any other software onto it (apt-get install)?
I think because the OP already has an rock64pro sitting around (with the PCIe slot already used? and/or no PCIe NIC)...
For the dumb AP role? I think that depends mostly on what kind of WiFI performance you want.
Apt-get will not work, but OpenWrt offers some limited set of installable packages via its opkg "packet manager" (in quotes because opkg is designed to be lean and some features one would expect from a full fledged packet manager seem to be missing). From an attack surface minimization perspective it seems a reasonable policy to try to restrict the amount of software/packages on critical infrastructure like a router.
Yes, the RockPro64 will do linespeed just fine. I would consider a PCIe NIC instead and maybe look at another distro for more functionality (better availability of software) but that's up to you. I have a few sites that runs FreeBSD + Dual Port Intel PCIe NIC.
As far as AP goes IPQ401* is decent, so is pretty much anything that uses ARM/ARM64 and mt76 (11ax might be a bit flakey).
Why a pcie nic? How is a little card going to match the wireless signal transmission of a wifi6 router?
Are there other distros that will allow me to run everything through wireguard with a killswitch? I know i can do this on android but i thought the point of openwrt is that all this networking configuration is easily done instead of having to manually edit IP tables and firewalls.
Because it only has one ethernet port, and i will need a 2nd to go out to the wifi6 dumb ap if i want a good signal, im not sure why everyone is suggesting a pcie nic, they have horrible signal strength in my experience.
Because it's more reliable and less prone to failure (at least in my experience), think of it as getting the possible cheapest tire you can get for your car or getting a "decent", both will take you 100mph but experience might be a different story.
If you want a GUI I guess OpenWrt is your best bet.