I'm not sure I can answer all your questions here... But I'll give it my best shot, based on my experience and knowledge. And, I'll say that you're being somewhat nebulous with the question (maybe you need to, so as not to expose you billion dollar idea). As such, my answer is really (admittedly) more likely to be considered a discussion point, maybe, than an "answer".
OIDC (OpenID Connect) is new, as is the IoT (Internet of Things). Enterprises are rarely bleeding edge, unless they are dragged into it kicking and screaming by a bigger enterprise partner. That being said, OIDC is built on top of OAuth2.0, so it has understanding out there, and enterprises are really in the take-up phase (IMO), and many of the purchased platforms (like my company's) support it at [current draft-1].
What I think is important to point out is that neither SAML or OIDC is "authentication". It's a standards-based method by which you can carry attributes from an authentication point to an application point that needs to KNOW who or what is connecting to it. Your users could connect one way, your "sensors" another. Or maybe both. Or maybe the opposite. If you're building the next trillion dollar social media site, do you want to limit the ways that your users can join up?
In reference to your question about OIDC and Sensors... I would suggest a certificate-based authentication system, if these things are truly just sitting out there on their own. Again, however, OIDC (and SAML) isn't an authentication system, really. It doesn't do the "front line" of the authentication - it provides a method by which an identity can be carried to the relying party based on a validated claim with a trusted partner. UUID may well be a good choice for the "username" of the device, but it certainly shouldn't be the "password".
Finally, I'm not quite sure what you're asking for with accounting. Are you wanting to charge a user for access to your IoT device streams with, say, microtransactions (interesting concept, if so). Again, neither SAML nor OIDC provide for something like this, at least as far as I am aware of. Accounting (and billing) would have to be built into the application.
HTH -- Andy