Storage is not an issue but RAM is, Qualcomm ath10k requires 256MB of RAM for two radios.hAP ac2 has the same wireless chip as the ac3. Most likely it's excluded from the compatibility list because of it's 16MB of storage.
The old revisions of hap ac2 did ship with 256 MB RAM, the only thing preventing wave2 installation is the limited storage space.Storage is not an issue but RAM is, Qualcomm ath10k requires 256MB of RAM for two radios.