I recently made a post discussing my move to Linux on Fedora, and it’s been going great. But today I think I have now become truly part of this community. I ran a command that borked my bootloader and had to do a fresh install. Learned my lesson with modifying the bootloader without first doing thorough investigation lol.
Fortunately I kept my /home on its own partition, so this shouldn’t be too bad to get back up and running as desired.
Not the person above, but if it is an issue you ever run into you are doing it “wrong”. Not really, but let me explain.
Having it on a separate partition has a few advantages like different mount flags (e.g. noexec), easier backup management (especially snapshots) and some other benefits like using your home for a new installation (like OP wants to) or it prevents some critical failures in case you accidentally fill it up (e.g. partial writes or services cannot start).
I often cannot decide on specific mount sizes either, because requirements may change depending on what you do. Hence I would just stick with some reasonable defaults for the installation and use some form of volume manager instead. If you want to use ext4, xfs etc I would recommend using LVM as it gives you a lot of freedom (resizing of volumes, snapshots and adding additional drives, mixed RAID modes etc) or there are btrfs, zfs or bcachefs to name the most common file systems which implement their own idea of storage pools and volumes.
Never should you need to resize a partition, there are more modern approaches. Create a single partition (+ a small EFI partition somewhere) and never bother with partitions ever again. The (performance) overhead is negligible and it gives so many additional benefits I didn’t even mention. Your complaint is a solved problem.