Afaik the new wAP AC (RBwAPG-5HacD2HnD) has similar specs to the cAP AC model (except that it does not have visible LEDs, it can also be powered via DC jack and it has an IP54 protection), for FCCID see.
reading the cAP AC support thread I tried a build for hAP ac2 from here . Everything worked fine, including 2.4 and 5.0 GHz wifi
the future official supported builds for the cAP AC should also work for the new wAP AC
the same as with MikroTik wAP AC (RBwAPG-5HacT2HnD). All 140+ of them.
but with 5hacD2hnd model...
The file openwrt-21.02.0-rc2-ipq40xx-mikrotik-mikrotik_hap-ac2-initramfs-kernel.bin was served via tftpd to correct IP (as seen in tftpd logs), but the device does not boot with 192.168.1.1, just dhcp IP with all IP services closed/disabled(?) on that IP....
What RouterOS version was on those RBwAPG-5HacD2HnD ? More than 6.44 ?
Do you still have those HAP AC2 builds anywhere ? The link from your post gives no results...
And yes, I also have those builds. Do you want me to upload them? Where?
BusyBox v1.31.1 () built-in shell (ash)
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|__| W I R E L E S S F R E E D O M
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OpenWrt SNAPSHOT, r14057-a28b8fecf6
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root@OpenWrt:~# cat /etc/openwrt_release
DISTRIB_ID='OpenWrt'
DISTRIB_RELEASE='SNAPSHOT'
DISTRIB_REVISION='r14057-a28b8fecf6'
DISTRIB_TARGET='ipq40xx/generic'
DISTRIB_ARCH='arm_cortex-a7_neon-vfpv4'
DISTRIB_DESCRIPTION='OpenWrt SNAPSHOT r14057-a28b8fecf6'
DISTRIB_TAINTS='no-all'
root@OpenWrt:~# cat /etc/openwrt_version
r14057-a28b8fecf6
root@OpenWrt:~# uname -a
Linux OpenWrt 5.4.52 #0 SMP Thu Aug 6 10:54:51 2020 armv7l GNU/Linux