You can load ClojureScript :advanced code directly into an ESP32 WROVER for execution upon boot, by creating a binary and flashing it to the JavaScript "boot ROM" area. This has the same effect as when loading code via the Espruino Web IDE, in the "Direct to Flash (execute code at boot)" mode, but flashing is much quicker and more reliable.

Here is a small program that uses enough to pull in data structures, etc, leading to nearly 100 KiB:

src/foo/core.cljs:

(ns foo.core)

(def m {:a 1, :b 2})

(js/print (reduce + (vals m)))

With deps.edn:

{:deps {org.clojure/clojurescript {:mvn/version "1.10.597"}}}

compile this program via

clj -m cljs.main -co '{:process-shim false}' -O advanced -c foo.core

Confirm that Espruino can run the resulting JavaScript by executing

espruino out/main.js

and confirming that it prints 3.

In the above example wc -c out/main.js shows that the file is 96503 bytes.

Create the first 16 bytes of the boot ROM in a file that has the size of the file as the first word followed by a word of all FFs and then the ASCII for .bootcde. If you create this in a file named header.bin it will have contents that look like the following:

00000000  f7 78 01 00 ff ff ff ff  2e 62 6f 6f 74 63 64 65  |.x.......bootcde|

Note that, in the above f7 78 01 00 is little-endian for 0x000178f7, the file size 96503 in decimal.

Concatenate this header with your :advanced JavaScript to create the boot ROM binary:

cat header.bin out/main.js > main.bin

esptool.py --chip esp32 --port PORT write_flash 0x2C0000 main.bin

In the above, replace PORT with your WROVER's serial port (something like /dev/cu.wchusbserial620).