I have not, thanks for the pointer. That is an interesting patch, it does two things:
The first patch to mac80211.sh I "indirectly" knew about, it enables the wpa_psk_file and vlan_file options that are necessary to specify, well, wpa_psk and vlan files. I have been using these options, I have already documented them, and without these options it would be very hard to get these files known to hostapd.
The second patch to hostapd.sh was yet unknown to me. It is basically an abstraction that compiles respective UCI options into wpa_psk and vlan files.
The UCI way seems quite a bit more verbose at first, especially if one were to use it for multiple PSK/passphrase variants. But the abstraction may help if the options should apply to multiple wifi radios. And I guess it would be a prerequisite if someone (not me!) would ever extend LuCI to support the mechanism. Directly editing the files on the other hand keeps the wireless config a bit more decluttered and allows it to be manipulated by external scripts (to rotate passwords, for example). It's a tradeoff, both ways have their use.
But this patch also answers the question since when these options are available in release OpenWrt: 21.02.
(And now I should probably add those new UCI sections to the wireless config wiki page, shouldn't I?)