glim is like Ventoy, but built on GRUB with much cleaner code and no blobs. Doesn’t work with as many ISOs though.

Any way you boot it, gparted should work just fine from a live ISO.

If you’re just testing things out, Ventoy should be fine. If you want full assurance nothing fishy is going on when installing, do it the old way and dd the image to the USB.

You use ventoy to boot into a live linux iso and then run gparted to resize, though there is a chance you have to do a non persisting install of gparted first.

Multi writer, KDE writer, Rufus, Mint stick. Take your pick depending on distro.