I found this is the only version for TP-Link Archer C900 / AC900.
Is there any updated openwrt firmware that can be used on this model without jumping through hoops?
nope, but if it's https://fccid.io/TE7C28HP then it's supportable if someone would put in the time and effort ( = you).
there's also I can't seem to find openwrt firmware for archer c2 v3 ac900
Got it. Unfortunately I'm not a tech person so I can only follow instructions step by step, if I understand it. Anyway thanks.