Exchanged iPhone still shows up on my device list

Exchanged my iPhone 16 Pro today in an Apple store for a different color. Pretty sure I hit the "Erase Data & Setting" (Factory Reset), enters Apple ID PW to deactivate Find My iPhone when turning it to Apple Store staff and the colorful Hello Screen popped up.

However, a few hours later, the phone still shows up on my iCloud device list unlike some other device which I returned / exchanged before. A bit freaked out, I hit the erase command in "Find My iPhone", got the "pending erase" message, and returned to the Apple store.

Spoke with the Genius Bar staffs and was told that it can happen as the erased the phone has not been connected to internet, and the erase command is independent from iCloud device removal so I should remove it from my iCloud device list to prevent access to iCloud.

Want to double confirm a few things with the community

1) In case that the iPhone hasn't been successfully reset when I was at the store, will the "pending erase" command still validate after I remove the iPhone from my iCloud device list?

2) There were no file in "On My iPhone" location of the returned iPhone. However, as it has been connected with my iCloud, will there be any local copies retained from iCloud on the device? And whether removing the device from my iCloud device list will remove access to the file (on the drive & local copies)?

Thanks in advance for your input.