One is to set up a XVC (Xilinx virtual cable) to work with Vivado and allow me to download FPGA bitstreams. I have had complete success with this using XVC-pico on a Pi Pico.
The other is to use generic JTAG to read and write NAND flash. I looked at this, and it seems impossible on the Ebaz board. At least the flash chips don't appear conveniently on JTAG as I thought they would. The Zynq FPGA and ARM both do, and a person could download code to run and do almost anything, but this was not the approach I had in mind.
I played with DirtyJTAG and Versaloon. Other possibilities are the Segger (either the clone I have or buying a genuine one). Another interesting gadget is the Black Magic Probe that you can connect directly to via GDB. You can buy a BMP or you can setup your own (the software is open source apparently).
Tom's Computer Info / tom@mmto.org