Stair Safety Gate Recommendations

One idea might be to look for gating for stairs made for large dogs. I did a quick web search and they do make them taller. I’d guess some might be more sturdy. If you have any friends with depots that have a connection to a vet hospital or large pet kennel, the empress at those facilities might know which brands are best.
If you think a sturdy rail would be enough you might have a swing-type rail, or a barn door type rail fit for across the opening with a difficult to open latch.

I am not clear on whether you want him to be able to get through the gate or trying to prevent him from getting through it. We have Standard poodles and have needed to limit their access up or down tge stairs periodically but they were able to jump over low regular gates, so we found taller gates that swing open by depressing buttons to release the moving section and eorks well for human operation with a couple of problems: they are held in place by pressure points on either side of the wall or stair knoel so the gate ends must line up with some side support. To do that means you are taking a rather precarious step at whatever level it is placed due to the gate using some of the stair step width. I would prefer one that didn’t have a solid bar across the bottom for that reason but without it the dogs can push it over, which might not be a problem for you.
Chewy.com is a pet supply house that carries many variety of gates that might work for you. They are reasonably priced and ship reliably quick. Maybe call them to discuss your needs after shopping online.

I agree @boppi that the bar that lays on the floor is hazardous. My son has a gate at the top of his stairs for kid safety and it makes you have to step through the gate down to the next step - it takes balance and some leg strength to do it.
A swing bar gate, or solid swing gate, see links, attaches to one side. A latch or “stop” would probably be needed for the other side.

We had a child gate mounted into the drywall at the bottom of stairs at our house. We removed the gate and filled/spackled/painted the not insignificant holes before selling a couple years ago. You could not tell we previously had a gate there.
https://gocorp.com/shop/stanchions/doorway-swing-gates/
https://a.co/d/1KoB3hF

Clearly stairs are not safe. Have you considered renting a hospital bed with guard rails for the living room for hubby and using a camera baby monitor for yourself for upstairs until you can find a long term solution.

@boppi the goal is for the gate to impede him being able to go upstairs while he is still ambulatory. After talking with a couple of our adult “kids,” and my husband about safety and options until we sell, we are going to convert his downstairs office by adding a medical bed. For now, we’ll have him shower 2-3 times a week at our daughter’s home, a nearby 15 minutes away.

Hi Elisa, attached are the gates we use now. They require someone to pinch the grey button and slide it back to release the midsection to open. It is a one handed action. My husband with moderate dementia can operate it although you could put a lock to prevent it from opening which of course might be a pain for you.
We had another type epen/close mechanism which was harder and my husband had trouble opening because it took two hands and was more complicated which might workbetter for you. If you start looking on chewy.com pay attention to how they open mechanism works.

I also want to tell you that “no rinse” cleaining cloths work very well for cleanup and bathing “kitty bath style” on a more frequent basis. There are several brands available on Amazon but the large, thicker ones are best.

@boppi thank you so much.