There are 4 repositories under lisp-machine topic.
Historical Emacs Software Preservation
LambdaDelta
Community maintained SUPDUP client for Unix
Macsyma
caar - the modern LISP machine
Lisp Machine base on Chez Scheme
CADR4 -- accurate model of the MIT CADR
Symbolics 3640 Microcode Explorer
Rust implementation of a Virtual Lisp Machine
Lisp interpreter written in C++