FYI, most fonts on Google fonts have not been commissioned by them, they are aggregating a lot of independently developed open source fonts. But if your looking for other sources, check Fontsquirrel or Fontshare
And if you give me some specifics, I'd be happy to recommend some specific faces.
Thank you so much for your availability! These are some features I've been looking for, in order of preference. I know that probably no font family satisfies all of them:
Open source
A monospace font should be included
The family, including the monospace, should at least have Italics, bold, bold-Italics
The monospace should have clearly different capital O vs zero 0, capital I vs lowercase l vs one 1
The family should include maths symbols like √∫⇒∧∨¬∞∑∏∪⋃∩⋂∈∉⊢⊨∅≠∝±≈≡∂∇↦⊆⊇≪≫⊗⊕∀∃ (preferably also in boldface; italics not necessary
The family should include the Greek alphabet (Italics, bold, bold-Italics), preferably with nu "ν" clearly distinct from v.
The proportional fonts should not look too "fancy" – I know that's difficult because subjective. As an example, Palatino and Minion Pro are among my favourite fonts.