This should be an easy one to implement, and would add an important bit of functionality currently missing.
The "Canvas Size" action should have the "Color of pixel at" feature for background color. Often you want to batch this and you need the background color to be dynamic.
"Colour of Pixel at position" is a good start - later on there could be additional methods to determine the background, e.g. colour that is most often used for example.
This has been implemented in "Batch Convert" beautifully but I'm disappointed that the "Canvas Resize" dialog for single image operations doesn't have it
AMD Ryzen 3 3300X 3.8Ghz, 16Gb DDR4, RX6600XT with Dell U2520D at 2560x1440@60Hz scaling 125%
Windows 11 Pro x64 23H2, Listary Pro, PowerToys and Wintoys