I agree - a proper eye dropper tool would be very helpful.
In Illustrator, I'm used to being able to choose the eyedropper tool by hitting the "i" key. From there, I can either click to select a color or Alt + Click to apply a previously loaded color.
This is WAY, WAY faster than the current method in Affinity. Addressing this quickly would be a huge help.
Very much related to this is the "Select Similar..." command in Illustrator. That is a giant time saver. I would love to be able to select all objects with the same fill color, or all lines with the same appearance or similar. This is really helpful and I've really missed it since I started using Affinity more.