You keep confusing the Hosting Service Provider (HSP) with the DNS Service Provider (DSP).
HSPs are for hosting web sites, etc.
DSP are for service DNS zones.
In order to get a wildcard cert, all you need is an ACME client that can update your DNS zone and a DSP that supports zone updates via API.
There is no requirement to even have an HSP - all you need is DNS (and ACME client).
So, stop confusing them together - I know they both contain the word "Google" but so does Gmail and that has nothing to do with this either.