Queue: is there a specific member in it?

Colleagues, please tell me the answer to my question.

Is it possible by means of the dialplan, without using external databases, to check whether a specific member is present in the queue?

Either I was looking badly, or there is no such function.

I can get the complete list of queue members as a huge comma-separated string.
But the problems do not end further - if I understand correctly, Asterisk does not have a string function for finding a substring in a string.

I believe that checking for a specific participant in a dynamic queue is a fairly common task.
How is this solved? Only through the base?

Thanks in advance for your reply,
Ogogon.

${FIELDNUM()}
${REGEX()}
: operator

Thanks. I also found regexp in xIf() functions.
And, alas, no specialized function?