ok, but wouldn't the tags still be resolved by browsers, even if they're not wrapped inside <html>? or is the point that it's not meant to be viewed through a browser? the overhead of the tags in terms of bytes seems fairly negligible, no?

HTML tags will be recognised by browsers even if the file is not wrapped with an <html> tag, but only if the file is served as html.

As I mentioned in a comment above, wrap the plain text in <pre></pre> tags, serve as html, then you can use links without adding any other html at all.

right - just removing .txt at the end should be enough even

I think tags would not be recognized by browsers. I just select the link (triple click) and right click > open link in new tab.

Yeah you're right, I just tested it on my site. Before I just tried it in Codepen, but I forgot that it autowraps everything inside <html> and <body>, haha