Yes, please do this!
Two things I think would be really important for such a “fund PureOS” campaign to succeed:
(1) Transparency about how much money has been donated so far. Everyone should be able to see that, and to know that whan a large enough amount has been donated then development will happen.
(2) Show clearly when funds have been used, and for what. This does not need to be advanced, it could be statements like “person X worked on issue Y for a week”, and you could point to gitlab issues where more details can be seen about what is going on. (There is already transparency there which is very good, we can see the gitlab issues which is one way we can see that development has now stalled.)
If you (Purism) do it like that, then I would donate a lot. I cannot speak for everyone else but I imagine there is a bunch of other Librem 5 owners who would also put in money if you do it like that.
Note that I’m not saying this only because it’s the right thing to do because transparency is good in general, it’s also that I think you will get more money that way. When it’s immediately clear how the money is used, more people will donate, and they might donate larger sums.
Another reason why I think this would be successful: everybody already knows that the developers you hire are excellent and that they are good at upstreaming and collaborating with other projects in good ways, so there is no question that the money will be well spent and that it will help not only to L5 specifically but also to the wider FOSS ecosystem.
I think if you do a “fund PureOS” campaign in a good way keeping in mind (1) and (2) above, then that will be better than us running some independent wild-west campaign on the side using Liberapay or similar, which was the plan I had otherwise. I would rather donate to an official Purism campaign, if it’s done right, with transparency.
Edit: curious to hear what others think of this, would you donate to such a campaign if Purism did that?