can you not consider an ex fire brigade "jaws of life" hydraulic pump ther generally run at about 700 Bar
or
https://www.oertzen-gmbh.com/products/high-pressure-cleaners/e-1000/
https://www.woma-group.com/en/products/powerful-high-pressure-plunger-pumps.html
or
https://www.oertzen-gmbh.com/products/high-pressure-cleaners/e-1000/
https://www.woma-group.com/en/products/powerful-high-pressure-plunger-pumps.html