CKeditor 5 Hook and form improvements

Dear all,

I'm using this amazing module on CKeditor 4 and it was so easy to create a custom module to alter the link form and add more features to this module. I have quite a complex form, with some dropdowns:

- Style of the button
- Color of the button
- Icons

- Tooltip Text
- Tooltip Color
....

Now that I have updated to Drupal 10 and CKeditor 5 I'm faced with the issue of implementing this form in another way. I've installed this module and tried to see where I could hook in to add some custom fields but could find how. I created a CKeditor 5 plugin but couldn't add my fields in the form, so I decided to hack your module to add my fields.

There fore I would find it quite useful to know how to create a custom module to add some fields in the CKeditor 5 form. It can be with a blog tutorial, or even some dummy module inside this module.

2 other requests, and I don't know if I should do a separate post, would be:
- The possibility to add some description/help under the fields (for the title or classes for example)
- The possibility to add a dropdown (it's actually the most important thing for me now). For example, for the classes, a dropdown would be amazing! Something we could configure in the custom module directly (no need for me for a Drupal interface)

I know this is a lot, and I'll work with what I have now. Let me know what is feasible and how I could help.

Have a nice day!