Questions about Linux-Linux dualboot

So I've had enough from partitioning my HDD between Linux and Windows, and I want to go full Linux, my laptop is low end and I tend to keep some development services alive when I work on stuff (like MariaDB's) so I decided to split my HDD into three partitions, a distro (Arch) for my dev stuff, a distro (Pop OS) for gaming, and a huge shared home partition, what are the disadvantages of using a shared home (yes with a shared profile, I still want to access my Steam library from Arch if I want that)

Another thing that concerns me is GRUB, usually when I'm dualbooting with Windows, the Linux distro takes care of the grub stuff, should only a single distro take care of GRUB? or I need to install "the grub package" on both? Do both distros need separate boot partitions? Or a single one for a single distro (like a main distro) will suffice?

Another off topic question, my HDD is partitioned to oblivion, can I safely delete ALL partitions? Including the EFI one? I'm not on a MacBook, a typical 2014 Toshiba that's my laptop