I understand AX does not allow for NV2, but the radios does also support AC and N and i would think it possible to port NV2 at least for these standards that is compattable with NV2.
AFAIK it's not radio hardware in AX devices which is incompatible with NV2, it's drivers issue: on AX devices it's only possible to run new (wave2) drivers, which are essentially drivers created by radio chipset vendor (so far it's Qualcomm only) packaged into ROS ... while on pre-AC radios older wireless driver has to be used and that driver was Mikrotik's in-house development. On AC devices it's mostly possible to choose between both drivers.
And NV2 is Mikrotik proprietary radio standard. Hence it's not realistic to expect chipset vendor to implement it in their (reference) driver. And MT so far declared they won't be doing their own wireless driver development any more.
The experience, published on this forum a couple of years ago, when new wave2 drivers came into life, was that new wave2 drivers perform better in many use cases, including some of which used to mandate usage of TDMA (i.e. NV2). Which means that with wave2 drivers it might be possible to run your long-range rural links on standard 802.11 protocol. But you'd have to test if that's actually true in your particular use case (and on all involved links for that matter).