I recently stumbled upon a random post of a frontend engineer titled; "Fullstack" devs be like with the meme of this posts cover image. A well known meme, perhaps you've seen it before in the context of the game of thrones seasons or "when the client asks whether it can be done cheaper". And in this context the message is implying something I don't entirely disagree with either:
It is far too common to call yourself a fullstack engineer while coming from a backend background since you managed to vertical center a div once (been there). Or vice versa when you've also created an api endpoint yourself being frontend minded. If I have to make an educated guess on the posts' author intentions it is his way of saying that frontend development is not something you easily do on the side or to say it in other words; that proper frontend development is something to take seriously.
I have to disappoint readers hoping to find the answer here to the never ending debate "do real fullstack developers exist" though since I think there is no resolute answer to that question - sorry recruiters ;).
At first thought a simple NO would be logically reasoning that it's almost impossible to get exact levels of mastery with back and front work. On the other hand there are ample people pursuing fullstack careers, especially coming from bootcamps though one could question the efficacy of those ambitions.
The lead frontend developer at my last company really was pretty resolute on saying that fullstack developers are often a "Jack of all trades, master of none" and one could argue that having to traverse learning curves on both sides of the medaillon equally will leave you with dept in neither. Which also carries a truthful element.
Instead I can make the case why for you being a 'real fullstack developer' - coming from either side should not be that relevant if your desire is to do full stack activities.
Be an engineer first, focus on the full integration of features and the experience on the smaller stack will follow. Start digging on each part of the application to make the solution perform. I recently had a case where parts of the frontend were feeling sluggish only to find out after tracing backend calls that I missed a crucial extension in my docker container. Or vice versa when I envisioned that my endpoint logic would be totally overcomplicated only to have this eureka moment wherein some quick shuffling and mapping on the vue component saved me hours of work. Bottomline is, if you really enjoy working on all layers of a feature at the same time and get somewhat proficient to build the right well formed performing integral solution you are a fullstack engineer.
Also realise that it is totally fine if you most likely are more of a '70/30' split stack engineer like I realise; The 20/80 rule learns us that that should be more than enough to deliver durable solutions anyway. Should you lack the experience on your smaller stack but still enjoy it just keep on building full stack solutions - claim some full stack tickets at your day job or do them in a pet project. Plus keep reading (dev.to articles for instance) to get inspired and keep up with the never ending stream of frameworks and opinions. Finally, remember that clean code is clean code in any stack.
On the matter of full stack job openings it is probably best to ask the hiring party what they consider to be fullstack. Are they looking for that jack of trades or someone with a keen eye for the full feature integration? Let them define the relevancy for fullstack as long as you are clear on what you like in doing fullstack. After all, fullstack engineers are real engineers.