Airtable doesn’t natively allow for dynamic filtering or extracting values.
So I don’t have an answer for you unless you did this in the low-code automation tool Make.com, which would allow you to split a string of text and extract the specific value that you want from it.
Otherwise, if you just wanted to use Airtable’s built-in formula functions, this would either be completely impossible or extremely tricky. That’s because Airtable has an extremely weak (almost non-existent) formula language. Airtable only gives us a very small handful of extremely basic formula functions to work with, and most of them are not very powerful. if it can be done, it would likely start by including the SUBSTITUTE() function, which is the only function that lets you specify an index value. If anyone can figure it out, it would be someone in these forums, so you’ve come to the right place.
If it can be done with REGEX, Airtable has some extremely basic REGEX support, so there might be some hope there from someone who is a REGEX expert.
You should definitely email firstname.lastname@example.org to ask them to include a function to extract a specific index value from an array or comma-separated string. Airtable is absolutely terrible about implementing customer feature requests, but in the hopes that Airtable’s executive management changes in the future, it would be helpful for your email to get in the queue.