You can find mt7922 on eBay by searching for "MT7922A22M". They're often sold by
disgruntled ASUS users who replace the mt7922 included in their laptops with an
ax210 instead. You can find additional listings sometimes by also searching for
ASUS' model number for the NIC instead, which is "AW-XB530NF".
I found a first-party listing for mt7922 [2], but it's been perpetually out of
stock.
Meanwhile, the 80 MHz brother of mt7922, mt7921, is readily available from
Amazon, and uses the same driver as mt7922.
And buggy.
Part of what led me to mt76 was bugginess in iwlwifi. It turns out that every
iwlwifi NIC that uses RSS (9000 series and newer, so everything from the last 5
years) will occasionally drop bona-fide packets when the RX queues get backed up
with (relatively) too many frames too quickly, which causes a number of
symptoms, one of which is stalls [1].
Another frustration with iwlwifi is that ax200 and newer use RTS/CTS for nearly
every frame, argh. And the logic which decides that is in firmware of course. 
I made a number of changes to mt76 both AP-side and station-side, and currently
on my mt7922 laptop I get 2.10 Gbps RX and 1.90 Gbps TX UDP throughput. This is
with contiguous 160 MHz bandwidth over 5 GHz DFS spectrum and MCS 11 rates.
[2] https://github.com/kerneltoast/kernel_x86_laptop/commit/ca89780690f7492c2d357e0ed2213a1d027341ae
[1] https://bugzilla.kernel.org/show_bug.cgi?id=216044
[2] https://lenovo.encompass.com/item/12936010/Lenovo/5W10V25826/