All of them need to do it. There maybe differences, like different number of versions of kernel supported, so less of backporting, but still distros have to provide fixed kernels.

With Gentoo I believe it is more fun, because of all the options gentoo provides out of a box. More kernels, more work to do.

    ls /var/db/repos/gentoo/sys-kernel/
    asahi-sources/       git-sources/         linux-next/          scx-loader/
    bliss-initramfs/     gnumach/             metadata.xml         udev-hid-bpf/
    cryptodev/           hurd/                mips-sources/        ugrd/
    dkms/                installkernel/       modprobed-db/        vanilla-kernel/
    dracut/              kci-dev/             pf-sources/          vanilla-sources/
    dracut-crypt-ssh/    kergen/              raspberrypi-image/   virtme-ng/
    genkernel/           kpatch/              raspberrypi-sources/ zen-sources/
    gentoo-kernel/       linux-docs/          rt-sources/
    gentoo-kernel-bin/   linux-firmware/      rumpkernel/
    gentoo-sources/      linux-headers/       scx/

When I used Gentoo the normal was to install gentoo-sources, which gives you the kernel source code but doesn't compile it. You then have to compile and install the kernel yourself without any support from the package manager.

If you're running on a different platform then perhaps you need the raspberrypi or asahi kernel