If not, and you don't want to set up dnsmasq just for Nextcloud over LAN, then DNS-based adblock software like AdGuard Home would be a good option (as in, it would give you more benefit for the amount of time/effort required). With AdGuard, you just add a line under Filters -> DNS rewrites. PiHole can do this as well (it's been awhile since I've used it, but I believe there's a Local DNS settings page).
Otherwise, if you only have a small handful of devices, you could add an entry to /etc/hosts (or equivalent) on each device. Not pretty, but it works.
If not, and you don't want to set up dnsmasq just for Nextcloud over LAN, then DNS-based adblock software like AdGuard Home would be a good option (as in, it would give you more benefit for the amount of time/effort required). With AdGuard, you just add a line under Filters -> DNS rewrites. PiHole can do this as well (it's been awhile since I've used it, but I believe there's a Local DNS settings page).
Otherwise, if you only have a small handful of devices, you could add an entry to /etc/hosts (or equivalent) on each device. Not pretty, but it works.