Launch your installation media again, get your internet connection set up, mount your current install, chroot into it, finish installing the things you forgot, reboot, profit.

How don't you have any tty?

Maybe your function keys are set to be multimedia at the bios.

Try ctrl+alt+fn+F{Key}

Another alternative is to boot from usb, chroot and install a terminal

Alt-F2 or similar maybe gets you a run dialog or alternatively pass the “init=/bin/bash” option to the kernel.

I see you got it fixed and other people told you about chroot, so you're all good for now. FYI, next time you install, follow the wiki. There's a package that they tell you to install during the initial setup that includes all the basic things you'll need, like terminal, a browser, etc. If you skip that then you will definitely have issues like this.

That Plasma is not letting you move to a new tty is "interesting"....bad KDE!.....no cookie for you!

You should still have vi installed by default. I would go the arch-chroot route, but if you can use alt+F2 to search programs, perhaps you can find vi. If yes, ! executes terminal commands. So either you can leave yourself a line in .xprofile to halt you before x loads sddm (or some other tricky thing like that) OR you could do :!pacman -S

I'm a suckless-st guy myself, but you'll need a browser to get to it one way or another.

Can I just say we're proud of you?

Launch Dolphin if you have it installed and press F4.

Edit grub at boot time if you are using it, wrote emergency at the end of the line.

If you have installed X, then check to see if you can select another session in sddm to launch X own window.

There are other ways to do it as well, f.eks. with kdesu and alt + f2

You can always boot back into your live environment (install USB) and chroot into your install to grab missing packages.

Do you have GRUB or another bootloader that lets you directly set kernel parameters on boot? You could try replacing "quiet splash" or whatever you have there with "text"