For Devs, do you upload your projects via self server or serverless and why?

You mean deployment? There are many ways

Self-hosted VMs, Containers, or real machines and also the same set of things managed by a Cloud Provider

Not serverless, you'll pay for that. Also it won't solve any of your issues regarding the scaling of real life data what is the only hard part. Severless is nothing else than a vendor lock in and the stupidest term ever created. I prefer to deploy on a vps. They can be very beefii too and are easy to backup and quick to order. Bare metal is less easy to back completely and order process takes a while. I could also add that vps is easy to upscale but many times you're forced to upgrade to a whole new package bevause just adding only a few gb ram is more expensive normally. Cool is that vpses are also available for cheap starting prices, like 4,- at digital ocean.

My advise is to use caddy as webservice for auto https (sub)domains and make it upstream to your projects who you will host in docker containers. So, you have one app on your server, the caddy server and a folder containing sub folders with compose file per project. Easy to move to different server if needed.

Btw, if you want a decent server for cheap, consider hosting a mini vps and let an old computer at home act as server with ssh remote port forwarding. I do this over a 4g connection even and works fine. The vps in this case is just the machine where the domain dns points to and the gatewat to your home server. Such vps cost 4,-. So if you have a old pc at home, you can have a very good price/quality situation.

I host molodetz.nl on a 4gb vps with two cores. It's responsible for the devrant anti spam system, my personal email, repository server, build server, gateway to my home server that runs ollama with a ssh upstream. Vps also runs a chatapp that can do around 2k messages per second or so with 6/8 LLM bots based on ollama / openai. With 4gb swap configured, this all runs very smooth. I have one command to deploy all applications at once and finally the repository server. A survey with not even that many specs is a already a lot of fun.