Looking for open source headless text to singing or better yet MIDI to singing software

Scoured the Internet using all available tools. All I've come up with is proprietary and obsolete software and/or GUI-based software.

My goal is to create an ElevenLabs type api but for singing.

Something like Flinger (dead) would be ideal.

If I can't find it I plan to write it but I'd rather not reinvent the wheel.