I added PSRAM support to ulisp-2.4-esp for the esp-32-WROVER modules (should work with other modules too, but I didn’t test it). It seems to work, even if it is not fully tested now.
This version incorporates a few patches to newsymbol (included in version 2.1 (?) to improve the use of Workspace-cells on systems with limited RAM) and compact-image (used by save-image) (see LARGE_WORKSPACE_SETUP symbol in the sources). Without these the extra memory made some operations of uLisp rather slow, because it was designed to run on systems with very limited RAM.
You can download this version of ulisp at https://github.com/Kaef/ulisp-esp .
Feedback is very welcomed.