Using a rolling shower seat or fixed shower seat in the shower can accommodate some users. Shower seat should be a height of 17" to 19". A small stool or plastic chair can allow the bather to sit while taking a shower and can be removed for users who don't use the seat to shower.
A curb-less shower is ideal for people using a wheelchair, walker or for someone who is at risk for falls and can be used by everyone regardless of ability. The opening to the shower is level with the floor and is sloped down to the The shower should be 36" wide for someone using a transfer seat and 60" wide for someone in a wheelchair to be able to turn around in or for assists.
There are also many lifts to look into that provide transfers in the bathroom such as hydraulic chair lifts, sling-type lifts, rolling transfer benches, drop in tubs that have a platform that serve as a transfer bench, etc. Choose fixtures and fittings that are comfortable and convenient such as things that are easy to control with a single hand motion and closed fist or motion control censored fixtures.