Is water inflow into the bathtub possible?

Hello everyone,
we are currently planning our bathroom in the new building. I find a concealed installation solution for the bathtub very nice. However, I would prefer not to completely "embed" the entire hose.
I don't know if I understood that correctly, but can I rebuild almost any tub so that the supply is via the overflow?
This way you could save a fitting on the wall. Do you have any tips regarding this?

Or would it be better to choose the surface-mounted solution so that you are better prepared for possible problems and do not have to tear everything open?

Yes, the inflow can also be through the bathtub. But do you then want to do without the handheld shower?

convert every tub like that,

Nothing is converted there, that is a feature of some tubs (integrated inlet).

Nothing is being converted, that is a feature of some tubs (integrated inlet).

Exactly, so the answer is "no," you can't just convert any tub. It has to be a tub with (option for) an integrated inlet.

I myself am not a fan of concealed fittings. They are not maintenance-friendly and I don't find them high-quality (I know I'm probably alone with that opinion). However, in the search for a bathtub faucet, we simply failed because all of them stick out from the wall like pimples and can get in the way while bathing. Therefore, we chose an integrated inlet. I hope it holds up.

Thank you very much for your answers. I came up with the idea of the inlet because there are such connection elements from nearly every company on the internet. So it sounded to me as if you could "convert" it like that, of course before the actual installation. If I now search for bathtubs with an integrated inlet, these are immediately significantly more expensive. That's why I am confused. I would also like to have a handheld shower. How else could it be implemented? I'm not really a fan of this original "simple" surface-mounted faucet. Thanks again