I went through and made a shortcut preset file for Affinity Designer, attempting to map its functions to my best-guess equivalents for Illustrator. I didn't really spend all that much time on it, and I am very new to Affinity Designer. So frankly, I'm not sure it's the best, or going to help much. I think there are a non-trivial number of differences between the apps, such that a mapping between them creates a Frankenstein-ian problem: the set of shortcuts is neither Illustrator, nor Designer. It's a hybrid.
You're likely transitioning between Adobe and Affinity for good, so it might make more sense to just learn the way Affinity does it.
But here are some of the wins as I see it – items that activate more closely to key functions in Illustrator (as of CC 2021):
File
Package
Place
Export
Document Setup
Edit
Duplicate
Illustrator uses CMD-J for "join paths" and CMD-D for "transform again." Affinity Designer contains its "Transform Again" feature as a subordinate function of Duplicate. And some other apps use CMD-D for duplicate. So it seemed to make the most sense to me for this shortcut to map this to CMD-D in Affinity. It's less of a hurdle for me since I use duplicate and Transform again a lot, and they are related functions.
TextV
Show Paragraph (panel)
Layer
Create / Release Compound
Beware: compound paths behave a differently in Affinity than Illustrator. You can achieve the same thing, but there is an extra step to get Illustrator's default behavior. Make a compound, and then select "subtract" in Affinity's layer palette for the item you just compounded.
Note: I have only tested this for very basic compound paths. YMMV
Lock / Unlock All
Hide / Show All
Convert to Outlines
Select
Deselect
View
Actual Size
"Panels"
Brushes
Color
Layers
Stroke
Symbol
Transform
Full Screen Mode
Tools
Artboard Tool
Does not respond to Shift-O like Illustrator. It is just bound to "O" and toggles with the Contour tool
Ellipse Tool
Point Transform
Toggles with the Node Tool using the "A" key
Crop tool
This is not a standard tool in Illustrator or a conventional reassignment in Affinity; but I seem to be bringing a lot of pixel images onto my canvas and want to crop them. So I made this respond to the "C" tool, and disassociated the corner tool.
Node Tool
CMD-J is now Join Paths
NOTE 1: Anywhere the Illustrator Equivalent was mapped, the default Affinity Designer shortcut may have been affected or removed.
NOTE 2: I may come back and actually write in the shortcut keys here for reference. For now you just have to know Illustrator CC 2021
NOTE 3: The biggest disappointment for me: Hide edges. Can't find an equivalent for it in Affinity. Seems blue outlines are going to render for the path elements of objects any time they are selected.
IllustratorShortcuts-FEB2022.affshortcuts