the debugfs command from the official extX-fs support package (e2fsprogs) has an rdump command to recursively extract filesystems in userspace.

/usr/sbin/debugfs -R 'rdump / filesystem_extracted' filesystem.img

(it had this since may 2000: https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/commit/debugfs/dump.c?id=2e8d40d562ec93d68505800a46c5b9dcc229264e )