WordPress notification reports

I had to make a standalone dashboard for WordPress.

I designed an interface to notify users of information messages (eg wrong user password) such as verification of forms and files or errors.

But I have to carry messages just like wordpress. It is carrying messages in the WordPress admin panel with I guess (transients).

(1) Is this true or did I get it wrong?

NOTE: As far as I know WooCommerce also uses a similar method while giving an error message on the frontend.

(2) What kind of function should I develop if I want to move the messages created by a method like (transients) and press the screen? So what should my road map be like?

For example: Should I follow a way like catching an event (in Javascript language)?

addEventListener - in event - removeEventListener
setTransient - when run getTransient - deleteTransient

Or should I do the same with PHP session? Which one do you think is healthy?