They chose not to after researching options. Pretty sure they decides account portability was a key feature needed and AP doesn’'t do this. As in taking your account and all your posts and data witj you to a new server. I assume there is a technical reason why this would be very difficult to add to AP/Mastodon otherwise they could have just added it themselves.
I don’t think any builds have been compiled yet. I have no real knowledge how, but but you could build your own by downloading developer tools an cloning the codebase. Probably better just to wait. How were you downloading Simple Mobile Tools previously?