By way of a report.

Stamps: on two intra-Schengen Ryanair flights there was no stamping of boarding passes for non-EU citizens. I specifically inquired at check in and both times CS agents told me that there is nothing that needs to be done, and that if stamps and passport checks were required, there would be a note to that effect on the boarding pass.

Carry on - did no see any carry on size checks at the gate or anywhere else. Our carry ons were the "usual size" (accepted on any major carrier but a bit out of spec for Ryanair) - no issue bringing them aboard. We did have "priority boarding". Those who did not have priority boarding, simply left their carryons in a cart parked next to the aircraft, and got them back at the baggage belt. Again, no carryon size checks for that group was evident and a few were clearly too large.

Overall, Ryanair was not bad (again) - except for that gawdawful trumpet music after landing.

YMMV