I personally prefer to stick to config files in whatever format is native to ecosystem (toml, yaml, ini). Env files fill the same role for apps which are config

I personally prefer to stick to config files in whatever format is native to ecosystem (toml, yaml, ini). Env files fill the same role for apps which are configured by env variables, but you don't really need to use env variables there. It was forced by Docker some time ago as a single supported configuration format, but nowadays k8s happily accepts configs and mounts them as a file, so why jump the hoops with .env -> vars -> app?