My cat loves the outdoors but hates wearing a harness.

We rescued a stray kitty via the cat distribution about 7 months ago. He would go back outside every night for a couple of hours to play with the other stray kitties outside and he would come back inside. Back in February/March he had suddenly got really bad fleas and an ear infection so we had to keep him in more and more. Till about end of April when we moved from Hawaii to Ohio. And he has been really good in our new apartment. He never tries to go outside. He is actually scared to go outside. But he loves looking out the windows and the sliding doors.

Even back in Hawaii I tried harness training him in hopes I could show him things like the beach or the forest bc he loves the outdoors and grass and flowers. But he hates his harness. He hates collars too. Ive been trying everything everyone else says. I kept it by his food bowl. I spent weeks showing it to him while giving him treats. And when we tried to put it on him he always always hates it. I see other cat owners find success and its so hard bc I don't want to push my boy into something he is scared of. He knows what it is now and runs whenever he sees the harness. Should i just give up? I feel bad about all of it. That he cant go outside anymore and that if i did try harness train him more I think he would hate it.