Tech savvy overview of the various "stealth" proxy/tunnelling/VPN protocols

VPN
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Recently I’ve been looking at various proxy/tunneling options that can’t be easily detected by firewalls.

I’ve found a bunch of stuff, but I’m struggling to understand how everything work. I found dozens of differtent protocols, some open, other proprietary; some have multiple names while some names refer to multiple protocols… Most open source projects I found have a vague, non-technical description of what they are and do. And most “free proxys” I can find that use these protocols, don’t give enough details to let me configure my local endpoint (wtf?).

I’m a software engineer / Linux sysadmin and got a decent understanding of networking (protocols: IP, TCP, UDP, HTTP(S)… software: SSH, OpenVPN, WireGuard, iptables, Nginx, Apache… encryption: simmetric, asymmetric, certificates… routing, NATting, and so and so forth).
I’d like to understand how proxy-related technologies work; not in a super detailed way, just enough to understand what kind of data my proxy endpoint sends: is it encapsulated into any other application layer protocol? does it incapsulates other protocols’ data within its payload? how does it handle the routing?

Could anyone give me an overview of the various protocols, like: Shadowsocks (AFAIK it’s just a SOCKSv5 implementation that sends its data in the payload of an HTTP connection?), ShadowsocksR, V2Ray, XRay, XTLS, VMess, VLess, Trojan, Naive, Hysteria, Mieru, Psiphon, Eclipse, StealthVPN etc? Are there any others I should be aware of?

And to conclude, why is this stuff so complicated? The various protocols are considerably different from each others, or is this just a case of different people implementing similar things in different ways and thus resulting in an XKCD 927 sort of situation?

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First, the idea that a software developer and sysadmin is asking on Reddit about several arcane proxy/transport/hacker/experimental protocols has me scratching my head. I mean the source for most (all?) of what you list is easily available.

In a commercial environment, the only time you would see most of those is if you’ve been rooted and the attacker has setup a tunneling in/out of your network. Some have been used to bypass the Chinese firewall.

Stealth VPN is a freaking commercial service. ShadowsockR is a dead project.

So I’m not sure what information you are looking for? I think most engineers who can answer this question would point you to the source code and leave it at that.