You basically create a github, put a dockerfile inside it with your nginx config, frontend files, backend etc., then push and the Cloud Run instance is built for you then deployed into production. By default you are paying only for active requests, when a http request hits your box GCP will wake it up, charge for the CPU time used for serving it, then leave it idle for free for about 15 minutes. If another hit comes in that interval, you have instantaneous response because the instance is warm, otherwise it will wake up again and see a few seconds of latency (ie. during the night, when you have few visitors etc).
It also scales up automatically if you have substantial traffic, you don't have to do anything other than design your application so that multiple instances hitting the same data storage (ex. Firestore) will play nice. It of course handles all security, versioning, HTTPS certs etc. for you, you are simply serving plain HTTP traffic within the GCP internal network and just make sure your own application (what you push to git) is secure.
The things you pay for are outbound traffic (for obvious reasons like warez etc.) as well as storage of docker images (Artifact registry, i think you only have 0.5GB free, about 3 alpine images), but you can easily set up a rule to auto-delete old images.
Overall, you can run a small business with daily/weekly updates for less than a dollar a month and hit 5 nines availability, which you will never achieve for a self-administered VPS. Sorry if it sounds like an advertisement, but it's just enormous value for a small builder.