How to make a plan for an apartment or tiny home that is designed and organized for a couple using a walker by one and a manual wheelchair by the other.
You will want to consider counter height in a kitchen, as it will be different for the two of you. Maybe accommodate the one with the walker and make sure there is a table at which the one in the wheelchair could chop vegetables, prepare food, etc. Obviously, your doorways will need to be at least 36" in width. Look at those tall bathtubs that have a door on the side, and design your shower floor to be at the same height as your floor with no lip/divider between. Or, have a wet room concept, where your shower is not surrounded by walls or glass - I did this in my new bathroom and love it. The shower is next to the tub and the drain is in the floor. You will want to have easy and unobstructed access to each room, so your furniture placement will need to accommodate pathways. Make sure that light switches and door handles are easily reached by both people. This website has many house plans which should give you a variety of ideas.
https://www.thehousedesigners.com/accessible-house-plans/?srsltid=AfmBOorzCy4jMbVpJv8_ev1VPAizou7PcZAy4L26rM-moSSr4k-FgbP6
Good luck to you.