https://atariage.com/store/index.php?l=product_detail&p=949

http://8bitworkshop.com/v3.1.0/?=&platform=vcs&file=examples...

https://archive.org/details/StellaProgrammersGuide

There is also batari basic, not sure how much more accessible or easy they could make it. The first link cartridges should work in 2600+