We had an FIV+ for many years. He had weepy eyes now and then that we used to wipe but other than that he was very normal and not prone to random illness.
We have him lysine and forti flora later in life that seemed to help him. But that was for older cat pancreas issues.
He was an outdoor cat back then and strong generally. Our current cats are now indoor only.
It would go away for a bit and come back. It never went away completely but it would just happen every now and then and have a flare up. He would go through a random week where he would sneeze a bit. But he never coughed or had any other issues. He was about 14 when he passed which isn't bad for a regular outdoor cat. At the end he got pancreatitis and his organs started to go. We made him as comfortable as possible. The vet may have said it could have been related to his FIV. It let was a while ago now. Everyone in the block loved Ferris, he was a kitty celebrity.