All Y could be indicative of a small aircraft. If that's the case, it's going to offload in 3-4 minutes and the wait will be negligible.

If this is a mainline aircraft which happens to be all Y, I have never had a problem asking someone to pass me my bag. It happens to everybody sooner or later and it only takes one in 6 people (presuming 3-3 seating) to be willing to help.

Even on FT, 1/6 people probably aren't unhelpful.

As to who gets the space, unless the carrier provides otherwise, there is no rule. That's true of F/J/Y, and so on. Some carriers reserve space for premium passengers and others don't.

But, self-help isn't fun and I've seen people get the boot for exercising it.