Mentra Live is indeed a camera + speakers + microphone pair of lightweight smart glasses - that you can build for.

Mentra Live runs AugmentOS, so you can control all the I/O (camera, speakers, mic) in your own app with the AugmentOS SDK.

Regarding use the backend service all the time: Most apps/developers connect through official AugmentOS.org servers and focus on building their apps, but you can self-host your own backend if you want.