Are there realistic looking and working portable toilets available?

I wish I had a second toilet solely reserved for grandma. She takes lasix and sometimes doesn't get off the toilet long enough I fear leaking myself.

Call a contractor and get an estimate. Toilets are fairly cheap these days. It's the plumbing and permits that will run up the cost. However, depending on the length of time the patient might be expected to use the toilet and the cost of the aid to remove the waste might make installing a toilet feasible. Bedside commodes as has been described work but do have to be emptied. Rarely does the person who used it, empty it.

We use a bedside commode. After he's finished (if it's poo), I put a cup of extra strength scented Kitty Litter in the bag before tying it up. I then put that bag in a second bag and tie it before throwing it away in a covered garbage can that I use only for this purpose. There is rarely any smell.

I used kitty litter box liners in the bucket underneath the toilet. I bought them at the dollar store. Was cheap, didn't leak and was easy to toss.

I use an elevated free standing toilet seat that has arm rests & place a tall plastic bucket underneath it. I put a capful of disinfectant in the bucket & fill 1/4 with water. The bucket is easily emptied after use & there is very little discernible odor .

There are camping toilets that flush, but they don't flush into the plumbing system of the home. They flush into a tank below the seat, and that needs to be removed and emptied out into the toilet every few days at least. I believe there are chemicals you put into the holding tank to avoid smells. Most of them sit low to the ground - they'd have to be placed on a pedestal of some type to be usable by a mobility-impaired person. Maybe there are some taller ones now - it's been years since I've looked into these.

"working" as in flushing? and portable? No such thing. Think about it.

Even a chemical toilet needs to be emptied eventually so I can't see any point in using anything other than a bedside commode, there are many styles available.