I'm worried about the license.

Flyon contains code from Preline which is "dual licensed" under the MIT license and a proprietary "fair" license.

> Preline UI is free for both personal and commercial projects, released under dual license terms "MIT" and "Preline UI Fair Use License".

See: https://preline.co/docs/license.html

They don't explain if "dual license" means "and" or "or". I suspect "and", because otherwise, it wouldn't make sense since MIT is one of the less restrictive open source licenses.

If it's the case, neither Flyon nor Preline are open source.