Is it possible to use URL Query Strings in Frontend Submissions to populate CFs?

Note: I think of myself as an advanced googler rather than an actual dev. I'm also not familiar with the features in those other products mentioned, so my apologies if I have misunderstood what you want to do.

However, I'm currently working on a project where I am saving custom info into hidden fields, which might be similar to what you want to do.

Currently, I am making some hidden custom fields in MB. They don't show up in the frontend, but I can save whatever type of data I need to them by hooking into rwmb_frontend_after_process (currently I am using MB custom table to store everything). Then, it is just a matter of getting the data you want to save. I imagine that you can write some regex type code in some php functions to get strings out of the url to populate the fields. There might be more clever ways, but that is where stack overflow can come in handy.

Hopefully that gives you a sense of one route to do this type of thing.

Great! If you end up getting a working solution it might be nice to post some example code to help the next person who comes along.

Also, in that vein, here is the link to the documentation for the hidden field type in case anyone needs it. I forgot to include it in my original response.

https://docs.metabox.io/fields/hidden/.

Here is a result I got for googling how to get strings out of URLs using PHP. Looks like there are a couple of helpful functions to do this sort of thing that can be put together. Depending on the info you are trying to collect, you may not even need Regex, which would be nice.

https://stackoverflow.com/questions/13907793/preg-match-need-to-get-a-string-out-of-an-url

In case you end up having to use Regex, here are some helpful cheat sheets for learning the syntax:

https://www3.ntu.edu.sg/home/ehchua/programming/howto/Regexe.html
https://www.keycdn.com/support/regex-cheatsheet