Gosh one can go in a lot of different directions when talking about sex and sitting.
For decades, babysitters invited their boyfriends over once the child they were hired to watch was gone to bed. Some didn’t even wait for that. But I’m not in that world, so I don’t know if it still happens. Are teens even capable of looking after kids now? Are they even allowed? I’ve heard of parents getting in trouble for having their twelve year olds look after younger children. It boggles my mind because that was a normal legal babysitting age when I was younger. It seems fourteen may be the age now depending on where you live.
Anyway, I’m not going there.
There are seat-like ledges in showers now that I’m sure aren’t just there to put shampoo on. I’m also sure more than one park bench has been used for more than sitting. Bleachers. I’m sure there were many reasons my high school decided the new bleachers needed doors to access them.
There are a lot of positions in the kama sutra that are rather seated. And there are a number of positions that can be modified for anyone who can’t walk. There are also many assistive devices beyond swings that can help you have great sex despite your challenges. I found this post that can help you find what you need if any of this applies to you whether due to an injury or something long-term.