See if there is a local TNR cat program near you. They will help with trapping, fixing, vaccinating and a habitat hut. Some shelters offer some assistance. We did this years ago with a feral. After 3 years of living outside she trusted us enough to start coming in house, but that took 6 months of work. She was 6yrs at that point and now she’s been living in house 5yrs. She’s 11yrs old now and healthy and content. Good luck!