pfSense

Domeneshop is the largest registrar for .no (Norway) domains with over 40% of all .no domains. Source (in Norwegian): https://domene.shop/about
Their API is already added in Acme SSL certificate.
Please add their API to the Dynamic DNS service also.

Their API documentation can be found here: https://api.domeneshop.no/docs/index.html#tag/ddns/paths/~1dyndns~1update/get
TL;DR: https://{token}:{secret}@api.domeneshop.no/v0/dyndns/update?hostname={host}&myip={ip}

I have already tested this from pfsense with "custom" service, but "hostname" is missing in custom service so monitoring this is a bit awkward.