Hello, @esmerlinm . . . you are welcome to apply to be a beta tester. This testing is for features that the development team are hoping to release for feature updates only. This is a fun and exciting thing to do to be involved in the future firmware releases.
As for actual development testing in the way of programming or developing, you would need to talk to @Wayne_Zhang by private message or through E-Mail to service@living.ai . . . wishing you good luck.