I'd like to add in that as of version 5.4.0 of e4mc (seems to be available for 1.18 to 1.21.6), it now added administrative commands like /ban and /whitelist, which could be useful to mention (considering normally with open to LAN you don't have access to that, as you also mention). This is especially useful as there's some groups out there who scan for all open e4mc addresses (even though e4mc has been increasingly patching exploits allowing them to easily scan these), and technically once the address is found anyone can join such a session. Knowing that you can whitelist and ban with e4mc can be quite useful in that case.

Also found a small issue on line 50:
you should use a dedicated server of using Open to LAN => probably meant something like you should use a dedicated server instead of using Open to LAN

I'm also thinking possibly of bumping the VPN section above port forwarding, because I think setting up something like Zerotier is more likely to universally work with less hassle (and then nothing to do on MC's end as you can just Open to LAN, and it also works for self hosted dedicated servers in which case that also wouldn't need port forwarding), compared to port forwarding where I feel like once someone is knowledgeable enough to make that work they're also more likely to have more advanced knowledge in setting the rest up, and are more likely to read further into this in general
So this is trying to account for perspective of potentially very inexperienced, less knowledgeable people coming across it so the easier more universally applicable solution is further up