Renovate the bathroom, ideas?

Hello,
we would like to renovate our aging bathroom. It is the main bathroom (upper floor, no visitors), where we currently have a shower, bathtub, toilet, and washbasin on about 6 m². The current layout is as follows:

The classic combination, as was often done 30 years ago, with the shower next to the bathtub.
We want to keep both since we need a bathtub but also want to use this bathroom for showering. There are no sloping ceilings, as the bathroom has a bay window, but the entire lower front consists of windows. Between the window and the toilet is currently a classic radiator, which does not have to remain there. We definitely need to replace the fittings and get a new shower enclosure. Additionally, two tiles are cracked. If I add everything up, it makes sense to me to completely renovate the bathroom. Basically, the layout is okay for us; we would just like a larger shower (currently 70x90 base). Also, the shelf space between the bathtub and window is wasted space for us.
Cabinets are not necessarily needed, as a cabinet is planned under the washbasin as well as a mirrored cabinet.

Of course, we could simply move the bathtub closer to the window and thereby enlarge the shower. However, maybe someone else has a clever idea on how to design it more smartly.

So I don't see much against moving the tub downwards and making the shower wider. I might also put in a wider sink and equip the toilet with a [Vorwandinstallation]. Maybe retrofit underfloor heating?

So, just moving the bathtub towards the bottom of the plan is currently also the favorite. Since we have to retile anyway and re-lay the wall connections, that should be doable. There are no other rooms connected above. Regarding the drains, we need to see how "floor-level" the shower can be and how far back the bathtub can move (the drain is relatively close to the shower). But that should all be manageable. Personally, I am a fan of bathtubs in front of the window since the room is rarely used effectively anyway. However, I’m not exactly sure what to do with the space between the bathtub and the shower. The shower can't go anywhere else, and placing the washbasin in between probably won’t work. The toilet would fit well there, but it is almost impossible to bring the drainage pipes to the opposite side.

There is already a pre-wall installation on the left side. It might stay exactly as it is, but I would like to move the toilet closer to the window to accommodate a larger washbasin. However, that would require a completely new pre-wall installation. At the moment, not much more washbasin fits there, otherwise the door cannot open anymore.

Regarding underfloor heating, I have to check. It definitely won’t be electric, and I don’t want to renew the screed either. On the one hand, underfloor heating is nice (we have it throughout the ground floor), but the effort is considerable.

No alternative suggestions?

;) ... which walls are allowed to be removed? Where could the access be relocated to? ;) Unfortunately, there aren't that many possibilities here with predefined connections, doors, windows, and requests for equipment.

I just wanted to make sure I don’t miss a good idea.

Would you build a narrow wall between the shower and the bathtub or would you prefer a glass partition? A tiled wall is certainly easier to keep clean, but then there is also less light in the shower. In terms of price, it is probably not a big difference.