Oh wow, awesome use-case. This actually uses my Switch Bluetooth Controller emulation project [0] under the hood for automating the button presses. If you have a RPi on-hand, you can grab a decent USB capture card for around $15 on Ebay or Amazon, last I checked, for a cheap(er) entry point into automation projects like this.
According to one of the authors on their group's GitHub, NaturalSpeech is being deployed exclusively for use on Microsoft Azure [1]. I might have missed a link, however, I think it's likely that NaturalSpeech 2 will follow the same path, seeing as the code and weights are seemingly not published.
The caveat with the above is that you'll need something to host it. You could use a computer on your local network or a VPS of some kind (DigitalOcean, Linode, etc all have cheaper plans for hosting).
Once you get Code Server running, you can add the URL to your homepage to remove the Safari URL bar.
After checking out Sketch, I don't believe they offer a one-time payment option any longer. They seem to have switched to a subscription service now?
I don't use software like Figma or Sketch often enough to justify an ongoing subscription, so I suppose Penpot might be the next best alternative for users like myself?
[0] https://github.com/Brikwerk/nxbt