While I appreciate all DIY projects hugely, I must say, that... VGA only? No DP or HDMI? Very sorry, but I've not had any equipment at home which would accept VGA in years. While some Amiga enthusiastic probably are prepared to buy some equipment just for Amiga, they are buying 15kHz compatible monitors as well so any VGA-only scandoubler offer very little.
This is of course only my opinion and I actually hope I am wrong
All homebrew stuff is always great.