@Melissa,
There are many interesting and useful plugins in the Moodle Documentation page about third party question types that are listed as only having old Moodle 2.x versions available. I think it would be extremely good if you, or someone else, were to update some of them.
Carl LeBlond wrote many very good Moodle plugins for chemistry, but they are mostly 2.x versions that have not been updated since 2015
I will be looking forward to your progress.
I could test your new versions (if you host them in GitHub) and update the Moodle documentation pages and include some images/examples. I am not a PHP programmer, just a Moodle translator and beta tester who would love to have more of these Moodle plugins available for the newer 3.x Moodle branches.