With plain linux that’s a bit complicated to actually dualboot. When booting windows grub just throws the ball to windows bootloader and it manages things from that on, but with grub you’d need to have two separate grub-installations on different partitions so that changes made in Arch doesn’t mess up stuff with PopOS (and other way round). It’s very much doable, but I suppose (without any experience on a setup like that) that if you just go with default options it’ll break something sooner or later and you need to pay attention to grub configs on both sides at all times, so it requires some knowledge. Basically you’d need a grub installed on (as an example) /dev/sda for the system to boot from bios and another grub instance at /dev/sda5 (or whatever you have) for second grub. They’d both have independent /boot directories, grub configs and all the jazz. It’s doable, but as both systems can access either one of the confgurations you really need to pay attention on what’s happening and where.

Mixing home directory with different distros can create issues, as things have slightly different versions of software and their underlying philosophy, specially when mixing different package managers, is a bit different and they might not be compatible with eachother. Personally I would avoid that, but your mileage may vary wildly on how it actually plays out.

For the partitioning, you can safely delete all the partitions, but you’ll of course lose the data on the drive while doing it.

If I’d need such a system I might build a virtual machine to run all the dev stuff and just connect to it from a “real” desktop environment. Essentially mimic a two separate systems where you’ll have a “server” for the dev things and a “desktop” to connect with it. Or if you want a clear separation between the two it’s possible to run a different window manager for each of the tasks and just logout/login to switch between the two and with some scripting/tweaks you can even start/stop services as required when you switch between “modes”. Depending on your needs it might be enough just to run development environment with a virtualbox and start/stop it as needed and adjust the actual desktop experience accordingly.