I had a very similar request from a regular provider when I asked about setting up a new meet.....
he asked for a half-advance to be sent via Venmo or Paypal or something......I don't have any cash apps set up on my phone and didn't want to set one up for this purpose.....I ended up saying as much to him, as nicely as I could, and he said he understood......I did tell him I'd give him direct cash in person, but we were 120 miles from each other at the time.......
the meet went on as planned about five days later and I paid the normal amount in cash.....told him sorry I couldn't help him out earlier and he understood (wife troubles, no place to stay, blah, blah......)