Just use a stainless steel pan and a pat of butter.
There's no option to not use fat/oil if you don't want non-stick.
Cast-iron is not a great choice for eggs because it holds too much heat, so if your temperature goes too high up you can't bring it back down quick enough and your eggs will crisp/burn. And both cast-iron and carbon steel are a pain to maintain (keep seasoned and avoid rust). (Cast iron is ideal for other uses though, particularly searing meat, where holding heat is the main feature.)
Also, the idea that a cast-iron (or carbon steel) patina is somehow non-stick is a myth that keeps getting repeated. It's better than the raw metal (and therefore quite necessary for those materials) but it's nothing like an actual non-stick pan. Nowhere even close. And you still always need a normal amount of oil for cooking in them, in fact just for maintaining the patina.
- clean well with strong soap and a metal sponge until it's one smooth silver surface
- put a few drops of flax oil on a paper and rub the pan with it (also inner sides)
- take off all excessive oil with a dry kitchen paper
- remove any non-metal handles from the pan
- open your windows
- heat your oven to the max and put the pan in for about 20 minutes
- repeat about 5 times
After using the pan, wipe with a kitchen paper. Maybe a little bit of warm water, better not. Never any soap.
You have the added bonus of being able to put them into the oven, and you can get a much better sear than on teflon.
Last year I tried switching to stainless but it was just too much trouble for my daily egg cooking. I just never figured it out.
I use cast iron for many/most dinners but I wanted the sloped sides and reduced weight for flipping eggs.
I still use the non-stick occasionally for things like crepes but moving from daily use to weekly or less seems like a win.
I have a Mauviel that I love, but the Matfer Bourgeat is better for eggs because it doesn’t have the steel rivets on the inside of the pan. Both are made in France and cost like $70.
This is a solid explainer on carbon steel pans: https://youtu.be/-suTmUX4Vbk
If you version of cooking is "put anything in the pan at whatever temperature and expect it to not stick" then stay with teflon because nothing will save you
The thing is, any more oil than that just stays in the pan. Fried eggs don't absorb oil.
So put plenty of oil in the pan, because it won't wind up on your plate. There's zero reason to skimp, otherwise you'll just get eggs that stick.