I can't speak for other ISFPs, but my experience is:
I do philosophize quite a bit, and I think about right and wrong, good and evil, and the question of what's meaningful and essential in an abstract & universal way, but I think this is Fi and Ni working together, not Fi alone.
Sometimes I actually push my idealism and the universal values I've built to the back of my mind and just act in accordance with what works. I have a significant streak of moral pragmatism in me. When I'm in concrete FiSe mode, I'm more likely to think about specific situations, often related to the here-and-now. It's less "what is universally right/good/true, and how can I apply these values all the time" and more "how can I maximize my own and others' well-being in this situation"/"what's the right/best thing to do in this situation" in accordance with which way my inner compass is pointing at that moment. The one very simple universal rule that guides my choices (not counting when I'm being selfish and impulsive) is that people's lives should be treated as precious (even if life isn't meaningful or precious in absolute terms) and I should try to enrich others' lives, or at least avoid doing anything that makes their lives suck more, basically.