You are definitely giving your cats the best life!Of my current cats have one former feral and one former stray and neither want to go back outside really. I have others that were rescued from outside but were either not out long or too young to really remember living outside so they don't really count. I have a catio we built and both cats that use to live outside are excited when I open it to them in the spring and summer (it's closed from late fall to late spring because it's too cold here in northern Canada), but don't have any interest in actually going outside past that. I also have one cat that use to be and indoor/outdoor cat and go outside daily (except most of the winter), and it did take awhile, like several months, for her to calm down once I stopped allowing her out. She would cry at the door to go out, but eventually she learned that it wasn't happening anymore. It only really gets worse over time if you give in and allow them out, then they will learn that they just need to whine and meow long enough and they get to go out.
The ones I have that currently try to (and occasional do) escape out the front door are the ones that have grown up inside. I do take a few out on a harness and lead, and one for actual walks. The one that goes for walks is a very outgoing high energy cat, she was never an outside cat so she has never free roamed only been outside on lead in a harness so she seems to understand she has to have the harness on if she wants to go out. If you do decide you want to lead train to take them for walks I do suggest starting young so they are use to it, I have a cheap small kitten harness I use until they get bigger. You should start the harness training inside anyway so if they do wiggle loose they are still inside anyway.
My catio is built on the ground, so they do get to step and paw in the dirt, rocks, and even have a bit of grass, catnip, and random other plants that sprout up in there during the summer. Since you said you have a screen porch what you could try is growing a large container of cat grass for them (an old litter box or the ones they sell at dollar stores work well if you want something smaller and movable) a lot of cats enjoy being able to just lay in the grass and nibble on it. I have catnip that grows around the catio so I also regularly snip leaves and, once it's grown taller the stems, for them to chew up and play with.
Our catio in the Mojave was open year round except during snow flurries and sandstorms. Our beloved cats spent a lot of time out there and loved being able to observe all the wild creatures, sniff the breeze, and lounge around, play, eat and relax in it!