I try to install nextcloud on localhost on my artix Runit, i use nginx with Php-fpm and mariadb as database. I follow the tutorial in YouTube and archwiki, there is configure Php-fpm service but it only for Systemd, i don't know how to configure it on runit. (https://mega.nz/file/cBVBTIKa#d4PrWcnA7dsZucETVkkCkFJ-GN-24aWIODDkg3zfA6Y)
Have you tried to look at php-fpm-runit package?