Pilates/yoga were good for core strength and stretching. If you want to start at home Yoga by Adriene on YT is very beginner friendly. I was never a fan of cardio or strength training but I did a bit of that too (it was a gym with various classes and instructors).
Also got a dog, it's a great excuse for daily walks.
One day I realised I was actually resting my head on the headrest in the car and wasn't uncomfortable. Until then it'd never felt right and made my throat feel tight at the front. I still have a way to go though, I have back issues and you don't fix 15 years of bad posture in 3 years.
Edit: I'll add after reading the other reply, at the start it's a struggle just knowing what good posture is. It doesn't feel right and natural, because your version of natural has been modified. You don't know how it's meant to feel. I found that exercises which exhaust certain muscle groups helped a lot. They gave up some of their grasp and let other muscles work. After a really heavy workout sometimes my back felt looser and more mobile and this helped me learn how it could feel.
Poor posture can be slowly changed and it is life changing, obviously worth it.
Surprisingly the tongue has some major effect on posture, especially on forward head posture. There are all sorts of tongue exercises that benefit breathing, posture and even the looks. Tongue should be basically resting behind top front teeth and slightly press up the palate. For exercises look up muscular imbalances and see if you identify any on your posture. But all things start at the feet though, if feet have a problem the whole chain up gets affected so pay attention to the whole body.