I finally have openZFS loading as a module with modprobe (still need to test that it's actually working correctly, but so far so good...)
I'm using the Armbian Lunar CI rolling release since there is a working Linux-Header for this kernel
https://imola.armbian.com/beta/pool/main/l/linux-headers-midstream-rockchip-rk3588/
After that, I essentially followed the instructions for building openZFS, but some minor changes to the META file for license and max kernel version.
I want to say thank you to all the Armbian team members for making such an amazing platform for SBCs. All my boards run Armbian.
here was the config command I used
git clone https://github.com/openzfs/zfs
cd ./zfs
sh autogen.sh
./configure --with-config=user
make -s -j$(nproc)
sudo make install
sudo ldconfig
sudo depmod
sudo modprobe zfs