In Europe there is, lightweight metal tubs on wheels or casters that drain out the bottom into a floor drain in the bathroom floor.

What size is the shower stall? Does it have doors or what on it?

NO. You are "we" not just you. I understand you want to soak. Senior living places are built in consideration of most of the age group to whom they appeal. Statistics don't lie, and you may be FAR more agile than average - but one single fall can change life and you don't need to be ancient for it to happen.

If willing to pay for a rip ? Consider a walk in type. And be willing to pay for it : ) if this is your very basic tub sized shower stall.

https://www.safesteptub.com/products/the-hybrid-walk-in-tub-bathtub-features/?phone=8776311617&promo=0146&campaign=312887305&keyword=walk+in+tubs&content=626537589598&gclid=Cj0KCQiA6rCgBhDVARIsAK1kGPLi3fw1v-T9OTg_wwcWG2SdCnNk2M056UJ1ywMTYwcjyyLlKX-rl94aAh7hEALw_wcB

Just remember that other person you live with - or the fact that you both may not yet even be ready for a senior community! Or you need a different community......: )

I have no advice but want to sympathize.

There are blowup adult size tubs on amazon might fit in your shower.

i suspect that the residence would not allow you to make such additions to your unit. It is probably a liability for them and they likely have not designed the drainage in the building to accomodate the capacity of your tub.

I feel for you. It is a real trade off when moving into senior residences. Some regular comforts of home are missing and you have to adjust to a new life. It is very common for them to not have tubs.