What/How/Who is funding PPP optimization efforts?

[vap0rtranz]

There is also the opensource way, where commercial companies fund opensource projects

That's ^ how it usually works. Apache Foundation, Linux Foundation, FSF, etc. raise lots of funding through donations. Donations are often tax write-offs for the donor (but not always).

Don't discount "volunteers". They're usually employed elsewhere to put bread on the table, as @bcnaz said. So they're juggling a job and the project too.

Pine64 brand is trademarked by the Pine Store Limited, so that company is incorporated somewhere if the OP is really curious. My guess is they're a B Corp instead of a LLC (despite the "Limited" company name) because of the hardware sales being profitable while the mission can be deemed as benefiting non-shareholders. (Kickstarter itself is a B Corp, BTW).

So Pine Store Limited might employ a few folks via paychecks from sales of hardware + funds raised via donors ... But I could be wrong.