The original YazFi developer (Jack Yaz) stopped development of YazFi
back in 2022. It wasn't until relatively recently that user Martinski took up supporting the occasional maintenance of YazFi and several other discontinued scripts. At the time YazFi was created OpenVPN was the main VPN of choice. For a good while routers had questionable hardware power to properly service WireGuard. So why bother trying to support something a number of the Asus-Merlin firmware supported routers couldn't adequately support? With YazFi not currently supported under 3006.102.x firmware and that firmware's Guest Network Pro feature having a number of YazFi type features, its understandable that further development of YazFi might have slowed as Asus moves forward with new routers on the 3006.102.x firmware track and moving older routers to EOL status.
If you really want YazFi to support WireGuard then ask
@Martinski their views on the possibility of adding WireGuard to YazFi. THere may be specific reasons (time, effort, money, Wireguard supported routers, etc.) why such support has not been added to YazFi. Otherwise you'll have to try the workaround(s) suggested previously up thread. Or get off the bench and try coding YazFi yourself to include WireGuard support. Shrugs.