Ikea FÖRENKLA might be a decent IcelandAir & RyanAir only carry on
https://www.ikea.com/us/en/catalog/products/90373613/

Product dimensions
Width: 13 ½ "
Depth: 7 ¾ "
Height: 20 ½ "


Width: 34 cm
Depth: 20 cm
Height: 52 cm

Samsonite Flexis 19" might also fit if the measurements are accurate but I suspect they measured the skinnier top than the flared base
https://www.ebags.com/product/samson...uctid=10697466
19.5" x 13.5" x 7.5"
The underseater also seems slim. It is hard to find an slim wheeled bag which fits under seats with IFE gear. They seem to use wheeled bag bases manufactured for carry-ons.
https://www.ebags.com/product/samson...uctid=10697478