No, for several reasons (drawn from experiences in math, I am sure in physics and other sciences it is even worse):
Even if one includes hidden download-sites and special access by university subscriptions, only sources at the low or medium levels are available in a sufficient amount. The contents of an advanced level are only insufficient there, even some of the decades old and basic ones.
Suitable and really good existing texts on the web can be found only if one knows very precisely what one is looking for. But someone who wants to learn needs to find the better stuff, which is in part outside his/her mental frame. In contrast, good texts, even if found, still become hard to detect because of the noise by shallow pseudo-substitutes.
Browsing a real library makes your brain detect very quickly much more information and orientation, e.g. experiments (by friends who tutor at the local university) with beginning university students who were grouped and then asked to look for literature (in physics) by web/library only, for an hour, showed a very huge difference. An other experiment with students showed that students using a library have much better learning techniques that the other, but the later don’t notice. Maybe it is a special case of this. On the interesting ways of how subconscious learning and “active” memory gets connected by seemingly irrelevant sensory inputs may play a role then, a famous extreme case here.
A very excellent recent book, with fascinating new ideas and superior readable intros into many themes, is the new edition of Manin’s “course in mathematical logic”. So I’d recommend that. But: Why “foundations”? Like “foundational themes” in th. physics, “foundations” are not an appropriate place to start, they are a bundle of very advanced research areas whose intuitions and ideas come from core fields of research. “Foundations” in the sense of “what is it, really?” can be exprerienced probably much better by studying a good piece of core math, like number theory. Cox’ “Primes of the form x^2 +n*y^2” or Khinchin’s “Three Pearls of Number Theory” is what I would suggest. If your mind prefers geometry, I’d suggest to browse a good library for some of the great projective geometry textbooks from the early 20th century.