At least for myself, I barely use any local first software. The software that I do use that is local in any important sense of the word is basically local-only software. I realize this every time I lose connection on my phone. It becomes pretty much a pretty bad camera compared to my Sony.
I live in a country were I have good 3G speed pretty much everywhere so internet connectivity is never an issue, not even on moving things like trains or boats. The very few times I have been flying or whatever I simply don't do any work because it's usually uncomfortable anyway.
This is the main reason I don't really care about local first and have been diving into Phoenix Liveview the last couple of weeks. The productivity boost I get and cool realtime apps it empowers me to build is more important to me than the dream of making local first web apps. A realtime demo of things updating with multiplayer functionality is a far easier sell than "look, the app works even when I turn on flight mode". And honestly, in like 99% of the time, it is also more useful.
I have done local first web apps before and it is always such a pain because syncing is a near impossible problem to solve. What happens if you and someone else have done changes to the same things like 2 hours or more ago? Who even remembers which value is correct? How do you display the diffs?
No matter what you do, you probably need to implement some kind of diffing functionality, you need to implement revisions because the other guy will complain that the changes were overwritten and so on. There is just so many issues that is very hard to solve and require so much work to be done that it isn't worth it unless you are a large team with a lot of resources. You end up with a complicated mess of code that is like git but worse in every way.
It's easier to simply say the app doesn't work offline because we rarely are offline and no one will pay for the effort required. Unfortunately.