Save Modern Team Site as a template & provision using Classic Team Site method (visible in SP Admin)

Yes, that's a very valid pointer.

The issue for me was that the PnP provisioning process seems only to be able to create Unfied Groups with a Modern Team Site, or, Classic Team Sites.  The MTS is all bound up with the UG on a 1-to-1 basis and not visible in SP Admin Centre etc. etc.  The CTS is disconnected from any UG and not fully featured with all the "modern" capabilities, only some of them being available.

What I wanted was one UG with two MTS's bound to it.  Creating a sub-site in the one MTS of a UG might have been an option but for the fact that sub-sites are not full-on "modern" (yet).  Also, the second site was to have its own site collection admin i.e. the site collection admin of the first site should not be able to manage permissions on the second, and vice versa.

I also wanted the consistency in the user experience of having only MTS's, not a mixture of MTS's and CTS's (I mean, who wouldn't want this!?).  So for the sites that are to be provisioned as standalone Team Sites with no UG attached to them, I wanted them to be MTS's - like the sites bound up with the UG.

So far I haven't found anything in PnP that can achieve these requirements - and I'd be very pleased if someone to show me!

The only process that seems to work is the good ol' "Save Site as a Template" as described above.  But my worry is that MS are frowning on this, as you highlighted.

If MS is frowning on it so much that it is unsupported, then I'll just have to pause the project and wait until the roadmap of UG, MTS, and CTS reveals itself in deliverables.

If the MS frown is not that it is unsupported, but "not best practice", then until the "best practice" comes along by way of the roadmap delivering a consistent usage of MTS's across UG's and standalones together with supporting PnP provisioing processes, I'll stick with "Save Site as a Template" and migrate to "best practice" later when it's available.

So the question to MS still stands:  Is using the "Save Site as a Template" process described above, to template the UG MTS and redeploy it into the "traditional" CTS world (visible in SP Admin Centre, etc.), a supported process?

And an additonal question now:  Is there a PnP way of templating an MTS from the UG world, and deploying it out as a standalone site in the "traditional" CTS world (visible in SP Admin Centre, etc.)?