Offline-local plus additional cloud integration is definitely viable in most cases, where the workflow is mostly local. You do have to either have teams developing for multiple platforms or limit yourself to one platform.

For offline-first the money isn't on the software, it is on the hardware and maintenance. So it isn't something that VC or other wild speculators would enjoy.

You'll make a living, maybe build a team and that is likely as far as it can go.

Of course: YMMV

It depends on who your customer base is and how much you hate them.