What would be required to implement a provider in a new language (not golang)?

Right now we don’t support native providers in anything other than Go - but you can write your own dynamic provider than behave similarly - I know that @bright-orange-69401 has written a lot of them in Python with his team

Yup ! my company is massively using DynProviders mostly as a means to "bundle" complicated resources together (e.g. we made a ProxyGateway for AWS API + Lambda together which involves ~ 10 resources) We also use them to implement new services that have no Terraform counterpack (or a lacking implementation) : it's not trivial but it's definitely doable