If you can write a web page that submits a user form and a server that writes that data to a persistent database ... I'm failing to see which part of the "stack" is unfilled. This is what bootcamps teach.
Yes, bootcamps teach you the basics of each part of the stack. I would make the argument that you aren't proficient in any of these areas, so to advertise yourself as such is misleading. I file my own taxes, but I don't refer to myself as an accountant.
I've yet to meet a bootcamp grad that can efficiently architect a relational database, for example. I know plenty of Sr. level front-end developers who wouldn't think to call themselves full-stack even though they know how to submit a user form that persists to the database. Same with back-end developers who know HTML, CSS, and pick your flavor of JS framework.
If you've worked in the industry, you know things change too fast to stay up to speed on everything. It's not impossible, but it's unlikely and unrealistic to have that expectation of someone once they are employed.
Being full-stack does not mean you are a HTML and CSS expert. Anyone hiring a full-stack dev should know that. Full-stack means you can create a functional web application. It doesn't have to be in the latest JS library.
Many non-tech employers careless about your stack, as long as the application performs the tasks they want and the cost is reasonable.
A full stack dev most likely won't be an expert in any particular area but should have a good understanding of the web so they can pick up different JS libraries, web frameworks easily.
You're missing the edge, which is very very broad.
Suppose your employer wants your web app to interface with an industrial PLC, or fetch data from a car's CAN bus, or talk to a vending machine (ironically the sort of machine that Java was originally designed for).
Most bootcamps don't teach enough fundamentals for someone to figure out how to write both client- and server-side code for those sorts of situations.
Or on the other end of the spectrum, could you write hypervisor code to manage the sort of mass-scale VM deployments behind most cloud providers? It would be very difficult to be an expert on the "full stack", if you think about it.
So...tl;dr, most of the application layer? Probably the physical layer too, any how many of us really work with the link layer?
I've yet to meet a bootcamp grad that can efficiently architect a relational database, for example. I know plenty of Sr. level front-end developers who wouldn't think to call themselves full-stack even though they know how to submit a user form that persists to the database. Same with back-end developers who know HTML, CSS, and pick your flavor of JS framework.
If you've worked in the industry, you know things change too fast to stay up to speed on everything. It's not impossible, but it's unlikely and unrealistic to have that expectation of someone once they are employed.