Appclips in iOS are a decent shot at that. But require it to be under 15MB, which is really hard to hit, especially if you use RN, but we'll be dumping RN to make this happen as a next step.

>>The issue is that people often forget to uninstall these apps almost all the time

Fundamentally though, iOS will auto-offload the unused apps for you (you won't get any notifications). For all intents and purposes, it is an ephemeral app already.