For anyone who really digged Heroku's CLI experience, fly.io is particularly strong in this area, I find. The ability to just deploy in a single command from any directory was a huge draw for me (even Render requires you deploy from a git repo - a best practice, sure, but I like the option).
Yeah, I see it from both sides. I lean towards being an independent developer doing a lot of prototyping so I like Fly's tolerance of quicker, less strict practices in this regard. Not had any problems with fly.toml so far, but my apps are relatively simple.
What CLI…? Just set up continuous deploy from GitHub from the Cloud Run UX itself. It’ll create a Cloud Build trigger for you and deploy every time you push to your desired branch.