The folks at the Jacobin JVM [0] project (a JVM written in Go) are working on the issue of size and the ability to have a fully functional JVM maintained by a small group of developers. Right now, per the latest post [1], they can run simple classes and expect to complete the interpreter in the next few months.

[0] jacobin.org [1] http://binstock.blogspot.com/2023/02/jacobin-jvm-at-18-month...