For the memes: RTFM

Pure Arch isn't going to give you what you want. EndeavourOS is probably a better option. Nice installer, a relatively kind and helpful community on their forums, and you can use the Arch wiki to fill in the gaps.

https://endeavouros.com/

But why? Sorry if that is a vague question. Of it ain't broke...

I mean, you don't necessarily need a fresh Arch install; I'd wager you could just switch to Arch in place by editing your /etc/pacman.conf and /etc/pacman.d/mirrorlist to Arch repos. You'd probably need to keep a Manjaro section at the bottom of pacman.conf to avoid breaking too many things at first. Is this a good idea? Probably not, but it'd be fun to try.

I am not aware of any guides, but I know that in order to get the terminal to look like Manjaro's, you will need to install the zsh shell with the powerlevel10k theme and zsh-syntax-highlighting. I believe they also use either zsh-autocomplete or zsh-autosuggestions.

At least, this was how it was configured back when I used Manjaro several years ago.

This one is great

I’m planning to switch from Manjaro to pure Arch, but I really like the easy setup Manjaro provides

Can't you remove the specific Manjaro packages/configurations? I did this when I installed EndeavourOS, I removed ever endeavour-specific package and my "about system" shows "Arch" instead of "Endeavour" now.

I believe that this way you don't have to lose any files.