This is the esp32/esp32s2 gcc cross-compiler toolchain, version 2020r2, compiled for 64-bit raspberry pi os, and packaged as a debian .deb archive.
Install with sudo apt install ./xtensa-esp32-elf_8.2.0-2020r2_arm64.deb
Remove with sudo apt remove xtensa-esp32-elf
Files are installed in /opt.
This package is for 64-bit raspberry only.
Build script: build.sh. Uses crosstool-ng.
Packaging script: pkg.sh
See expressif doc: Setup linux toolchain from scratch