This looks like an interesting idea, specically to make sure the initial engagement with the user, so that they see the highly personalized call out message next to the bot widget button and click on it.
From the implementation and usage point of view, I think it will be easier to do this based on URL params on the link. So if you have some added URL params in the parent page link, the bot widget code can pick them up and use it to compose the final call out message, with the user/product/other etc… info in it. with some default values in place, if the URL params are missing.
Would love to know how many other people will use this feature.