One solution; treat open source like a VC.

Companies take a "FOSS/FLOSS" round -- in exchange for using community property firms would put ~7% of equity in escrow, that would be used exclusively to fund these efforts.

https://motherboard.vice.com/en_us/article/43zak3/the-internet-was-built-on-the-free-labor-of-open-source-developers-is-that-sustainable