You can request your service to be whitelisted: https://www.sk.ee/en/services/validity-confirmation-services...

Pricing is here: https://www.sk.ee/en/services/pricelist/certificate-validati...

So it's not quite as simple as Google or Facebook oAuth. But the government does support the idea that if you want then add this as a login option to your forum for dogs or an e-store for sweaters.

The main value is still in the fact that the authentication gives you the ability to create legally binding contracts that get signed online.