The few models of unlocked pixels that I've seen are all usable globally as far as I know.
These are the specs for the Pixel 9
5G mmWave + Sub 6GHz Model G2YBB42
GSM/EDGE: Quad-band (850, 900, 1800, 1900 MHz)
UMTS/HSPA+/HSDPA: Bands 1,2,4,5,6,8,19
LTE: Bands B1/2/3/4/5/7/8/12/13/14/17/18/19/20/25/26/28/29/30/38/40/41/48/66/71
5G Sub-6 : Bands n1/2/3/5/7/8/12/14/20/25/26/28/29/30/38/40/41/48/66/70/71/77/7843
5G mmWave : Bands n258/260/26144
Dual Band GNSS
GPS, GLONASS, Galileo
https://store.google.com/product/pixel_9_specs
It has a nano sim slot. Confirm which bands and sim card sizes are used in the region you wish to move to--Pixels don't have every band. Buy from the google store or best buy.
I'm pretty sure phones know to automatically utilize more/different wifi & cell frequencies abroad. But, I'm just a hermit that lives under a rock.