What value is added by swapping Docker out for an alternative on ECS? It's (at least as I understand it) basically an implementation detail, and well beneath the "covered by AWS support, don't touch" surface
Are you saying differences between Podman and Docker are uncommon? My untested assumption is that they're not uncommon just given how new Podman is. Testing is nice but you don't want to have to wait for that to run to find issues that you could make immediately obvious without it.
It’s also not something you need instant feedback on continuously while you work. The kind of things switching container runtimes will expose are unlikely to get caught by your local tests anyway so you’re most likely to only find it on your servers with lots of data and higher activity anyway.