All true, but not what will be mentioned if you enter your Aer Lingus PNR into their app or website ("no checked bags, 10kg carry on to be checked in")

I almost always have a 20kg bag to be checked so I print out the Avios receipt so I can show it to the check in person at the counter as at least it shows the 20kg bag included in case of any issues.
After they check you in, the boarding card says "Carry On Bag" so you're good to go and should even get priority boarding.
I'm not sure what the kiosk will spit out as a boarding card, or if it will allow you checked bags without manual intervention. Perhaps someone can enlighten us.