As a small start up when we ran into a similar problem while using google domains, they gave us a very hard time with bad support...something we could not afford then. I dont have a good alternative but wanted to mention this experience with google domains. Hope that helps.
Yes, all of these possibilities are under investigation. We have just recently secured ICANN approval to be a domain registrar. With our scale, this has become important now.
It is more likely Zoho is getting into/already in the business of selling domains and hosting as part of their portfolio and that's why they are becoming a registrar.
This isn't really a problem for companies the size of Google - while they may well refuse service to competitors or prohibit usage via terms of service, if they do allow a competitor on board there's no way they treat them any differently - there will be huge legal ramifications of they do.
For most of history Google offers essentially no support. Recently Google has started making phone support available for Google Ads (AdWords) putting a contact number on their customer facing website.
Maybe domains registered more recently work differently, but my Google domains use a random user account generated by Google for eNom (the provider they were contracting with at the time). That makes each domain it's own virtual customer (I couldn't just login to eNom or Google see a list of all my domains). I need to log into Google Domains as a separate account for each domain, and then that takes me to GSuite which links to eNom.
Also, last I checked, unlocking a domain for transfer to another registrar required emailing Google/eNom. There's no interface for it. For a while the entire UI to choose to cancel a domain just disappeared as well.
