Q: Custom fontsets and using a non-default fontset

[Soham Gumaste]

Hello,

Recently I got too curious for my own good while messing with emacs
(as one does) and discovered fontsets and transparent usage of
multiple fonts for different unicode points/scripts/ranges.

I discovered this [1] reply by Eli about *not* messing with creating
your own fontset and rather just using the default "fontset-default".
I did notice I am unable to set my own fontset as the default or the
one in use as given by the frame-parameter 'font.

How do I learn more about emacs fontsets? Is support for user defined
fontsets something thats in the works, or is it just an internal API?
The reply in [1] is around 6y old which is why I am curious about the
current state of this. A use-case I have in mind is switching to a
non-programmer fontset for presenting Org mode documents with
org-present.

[1]: https://www.reddit.com/r/emacs/comments/9l3n3y/comment/e750a2x/

Thanks
-- 
Soham Gumaste
sohamg2@gmail.com