pages and faux directory structure

Hiya! I’m sure I’ve come across a way to do this, but for the life of me I’m not quite connecting how.

Here’s what I’m trying to do:
1 – have tld.com be a static page (know how to do this)
2 – have pages be tld.com/pagename/ (also know how to do this)
3 – have the blog section (all posts) be tld.com/blog/ with index page and not affect everything else. This is where I’m stumped. Any idea or pointers in the right direction? I know there’s this: https://codex.www.ads-software.com/Giving_WordPress_Its_Own_Directory, but I don’t know if it will look how I want without affecting #1 and #2.

Even a “sorry, not possible with one install” would help, because then I’d know if it were even possible or not, and I could stop banging my head on the desk.