What needs to happen for that to occur? I just picked one up to play with after years of Mikrotik and a long-ago Netgear WNDR3700v2.
This thread contains 20 posts, I'm sure the picture will be clear(er) once you've read them all.
You're also asking a deregistered user.
The tool changes that added support for Archer AX21 v4.6 got pulled into the 25.12 release branch recently. That should also support AX1800 v4.6, including flashing from stock firmware using factory.bin image. This hasn't made it into a point release yet, but you can use a 25.12 snapshot image:
factory.bin: https://downloads.openwrt.org/releases/25.12-SNAPSHOT/targets/ramips/mt7621/openwrt-25.12-snapshot-r32961-78c88ce188-ramips-mt7621-tplink_archer-ax21-v4-squashfs-factory.bin
sysupgrade.bin: https://downloads.openwrt.org/releases/25.12-SNAPSHOT/targets/ramips/mt7621/openwrt-25.12-snapshot-r32961-78c88ce188-ramips-mt7621-tplink_archer-ax21-v4-squashfs-sysupgrade.bin
You can also try a main branch snapshot image, but those likely won't be as stable.
Caveat: I don't have an Archer AX1800, so haven't actually tried it on that device. I have only tested it on Archer AX21.
Thanks, I'll throw a snapshot onto the guinea pig router that I picked up (from a store clearancing their small number of tp-link devices) and see how it goes.
I'll also read through frollic's links, I just wasn't sure what the process might be for "this isn't really new hardware so much as a slight variation with a few additional identification strings needed"