Is friskies okay for my ragdoll?

I saved my ragdoll cat about 3 weeks ago from a not so great home. He has been very picky with food including treats. I initially bought him IAMS which I’m pretty sure is healthy and “expensive” food. He didn’t eat a single bite of it. I bought him Fancy Feast pate’s and some Sheba wet food that he also refused to touch. I gave up and bought 2 Friskies dry food flavors and he LOVES both. He doesn’t overeat or anything and drinks LOTS of water. He drinks his fountain water for 3-5 minutes 5+ times a day (I have 2 other cats and they drink way less water than him but they like wet food). I’ve tried slowly mixing in healthier options / wet food and he refuses to eat unless it’s ONLY friskies. From my research it seems like most people dislike friskies and that male cats can also have bladder issues from bad food so I wanna make sure I’m feeding him well and he doesn’t get sick. So far his health and litter seems normal and he’s very playful and happy (but it’s only been 3 weeks). Any advice?