I have one device where I didn’t upgrade the oldish WiFi 5-card by now 
I think using Turris Omnia is still cutting edge (there is no other upgradeable board that has nearly native OpenWrt and is actively supported) and therefore looking for the best upgrades is a natural thing to do. Even though the most recent upgrades have been deployed only one year ago…
But back to topic: looking at the data rates that WiFi 7 offers I fear our beloved Turris Omnia will not serve the next gen WIFI speeds anymore. Built-in mPCIe can deliver 2,5Gbit/s which is exactly the speed the SFP supports. So serving WiFi 6 5GHz 4×4x4 is fine. But anything beyond cannot deliver higher speeds.
You might in special areas get a better coverage using WiFi 7, but that could also be done via good external antennas and WiFi 5/6.
So - sorry, but upgrading TO (and even less MOX) to WiFi 7 doesn’t not make much sense to me.