I have one drive, 1tb with Pop_OS, and another, 500 on to which i want to install windows. (I know, I dont like it either but I want to play VR games via link cable cause ALVR is really mid)
So, I put the ISO on a drive with ventoy, booted it up, got it all going. started to install windows on the empty drive. So, after the five steps it kicks me out of the installer and now, I can't acess the second drive. Even through moving the boot order on BIOS, it always loads me into pop os. The only time it ever didn't do this is one time where it seemingly randomly gave me boot options, two of which were Pop_OS and one was "windows boot manager", which when selected turned off my computer and promptly i booted right back into Pop_OS. Can anyone provide some advice? TIA.
Ah I think Windows does this "helpful" thing where it installs its bootloader into the ESP of any drive if it's already present rather than the drive you explicitly told it to install onto.
You didn't have anything in it yet, right? Unplug all other drives and then re-install Windows onto the drive. It should work as expected after that.
IIRC Pop!_OS sets the systemd-boot timeout super short; you have to hold a key after the firmware is done or something to get to it reliably or simply increase the timeout (1s is enough, I have it set to that on my systems). systemd-boot should give you the option to boot any windows installation though, it can auto-detect them.
Well it's there at least. Hmm.
I don't know a whole lot about windows but you can certainly get back to those boot options you saw before by pressing shift while booting, which will open the GRUB options. I'd give the windows boot manager another shot from there.
If that ends up working you can change the grub settings to wait for input instead of automatically booting pop. If that doesn't work then something is probably wrong with windows and I would just try reinstalling since it sounds like you don't have anything on there yet.
There is a niffty Boot manager called Refined. This is what I use even though I installed Windows after Linux and had many kernel panics, but it does the job well since it scans your boot drive every time you Power on your machine. Here is a link. Just download the CD-ROM version, put it in ventoy, boot from it, and the rest is easy. You already are a linux user, you can figure it out.
I also advise you to disable Windows updates if you can, and I mean all updates, because they can mess the boot order. If you use Windows to play games and games only.
Edit: You can also install it from your distro package manager if you can access your system.
Applies to PopOS the same way, except for installation steps involving pacman. I'd revommend going with systemd-boot instead of grub, not sure what Pop ships.