The other remotely similar service, Tidelift, has unacceptable terms and conditions: for the compensation they decide "at [their] sole discretion", "[i]f you do not satisfactorily provide the Services, Tidelift may, at its option and without limitation, (a) require you to immediately re-perform the applicable Service at no additional charge; and/or (b) reduce the fees paid, or due to be paid, to you for the applicable Service in an amount commensurate with the cost to the Subscriber to cover the breach and/or the cost to Tidelift to assist its Subscriber with covering the breach." Quotes taken from the May 2022 "Lifter Agreement", which I was asked to sign for the monthly equivalent of what a professional charges for 30 minutes of work.
I hope that Ringer will prove a real contact point between Free Software professionals and professional users.