I implemented a HTTP/2 library for .NET (https://github.com/Matthias247/http2dotnet). It took quite a lot of time and dedication to get it spec conformant. I doubt that most employers (apart from some CDN) would have allowed me spending the time to get it to that level. And yet it still has lots of potential for improvement.
HTTP/3 might be even harder (I haven't read the spec yet, but the whole UDP assembly and inclusion of encryption sounds more complicated).
Compared to that building a small HTTP/1.1 library or a framework around it is much more approachable and might be also more rewarding.
I implemented a HTTP/2 library for .NET (https://github.com/Matthias247/http2dotnet). It took quite a lot of time and dedication to get it spec conformant. I doubt that most employers (apart from some CDN) would have allowed me spending the time to get it to that level. And yet it still has lots of potential for improvement.
HTTP/3 might be even harder (I haven't read the spec yet, but the whole UDP assembly and inclusion of encryption sounds more complicated).
Compared to that building a small HTTP/1.1 library or a framework around it is much more approachable and might be also more rewarding.