Working with an ath79 device that has 16 MB of flash available and an ath10k radio (Archer C7v2), with no "extra" packages from
master (meaning no LuCI and no web server)
- 4,391,714 -- Overall sysupgrade image size (kernel, ROM)
Add aircrack-ng (OpenSSL is default)
Add python3-light and python3-pip (be aware that -light doesn't have many "normal" Python libraries)
Add python3-pip (be aware that only "pure Python" packages can be installed by pip)
So it would be possible to fit all of that into an ath79 device with a 16 MB flash where the majority of that flash was available to OpenWrt. Doing that for the qca9563_ubnt_unifiac would require some careful examination of the boot loader's behavior (as it might try to boot from the "alternate" firmware under certain situations, resulting in a soft brick) and potentially "stealing" the alternate-firmware's partition for a single, larger firmware partition
label = "firmware";
reg = <0x070000 0x790000>;
compatible = "denx,uimage";
label = "ubnt-airos";
reg = <0x800000 0x790000>;
I wouldn't attempt it without full backups of the flash and serial connectivity.
Conceivably you could allocate 0x070000 - 0xf90000 for firmware, a little more than 15 MB.
NB: Do not overwrite the bs, cfg, or art partitions!
Assuming that the U-Boot could be made robust to never try to boot from the alternate firmware, it might be a couple evenings of careful work to change the DTS and add a "custom" device definition for the expanded use of flash.