I mean, I don’t see an issue with hiding the casting of a spell from people. I do think it should probably be the other way around for players (do a slight of hand to hide the semantic/material components, and beat passive perception), but in principle I don’t see why you shouldn’t be able to hide those?

I tend to rule that any components are “assumed to be in the materials pouch”, unless there is a significant (relative to party wealth) gold price attached, in which case they need to be bought. In practice I found that only really seems to apply to resurrection spells.

From there, the only thing that matters to me is can you reasonably perform or (roll to hide to perform) the semantic and vocal components, as well as get out the materials of your materials pouch in your current state.

In practice this means I can ignore components 85% of the time, but can still temporarily de-power my players if needed for some reason.