Note: I am operationally defining a "family" as systems with between which there is a vast majority of mutual compatibility in software terms, and they acted as, for all intents and purposes, a single "generation" of handheld, regardless of upgraded models. GB and GBC are considered the same family, DS and DSi are considered the same family, and so on. Some of their upgraded systems are a little more or a little less mutually compatible, but I don't think I'm being very controversial as defining them as a family.
If we include secondary displays, the DS and 3DS secondary screens are both 4:3 ratios, which is the only reuse I could find. I was unable to find data on game & watch resolutions easily, so if anyone has that info it would be appreciated, although I don't usually consider that to be a proper Handheld gaming console in the same sense the others are because it didn't have interchangeable carts.
- Game Boy: 10:9 Ratio (160 x 144)
- Virtual Boy: 12:7 Ratio (384 x 226)
- Game Boy Advance: 3:2 Ratio (240 x 160)
- DS: 4:3 Ratio (256 x 192)
- 3DS: 5:3 Ratio (400 x 240)
- Switch: 16:9 Ratio (1280 x 720)
If we include secondary displays, the DS and 3DS secondary screens are both 4:3 ratios, which is the only reuse I could find. I was unable to find data on game & watch resolutions easily, so if anyone has that info it would be appreciated, although I don't usually consider that to be a proper Handheld gaming console in the same sense the others are because it didn't have interchangeable carts.