AppPlatform and managed databases - newbie

Hello all, I am a very junior web developer and I am building a kind of ambitious project for my small family business, but I am wondering if DO would be the right choice for me.

The app is basically a CRM with some extra bells and whistles, like file storage and management, a bit of IoT to use remote printers, etc.

I already have a good chunk of the frontend using the Quasar framework and am comfortable building the backend with node.

My plan is to develop an “Environment” where I can host the business static website, and at the same time host the business Postgres database and app server.

I think the easiest way to achieve this would be to just get a server instance and have it do it all, however, I am quite junior so I am good with front and back end development, but I know very little about apache/nginx and I know nothing (I am a bit scared to be honest) about security and hacking.

I started developing this app as a web app using Firebase, but I found the noSQL database a little limited in functionality. I am using firebase Auth though, so I dont know if DO has an auth system or I should stick to google only on that.

The question is if using DO AppPlatform would be able to provide me with the security management and all the resources that I need for this to work at an affordable price? / is there a way to have my own server instance but have the security managed by DO? / If I dont want to manage security should I stick to some other service like firebase?

Any info/suggestions would be really appreciated, just remember I am a bit of a newbie.