if you can buy the GTX1650, ignore the
R5 2400G = 4 cores 3.6 GHz base 3.9 GHz boost clock RX11 Vega graphics
for the card is far superior to onboard graphics.
So, it's a battle for your budget, when it's time to buy, of the the
R5 1600 = 6 cores 3.2 GHz base 3.6 GHz boost clock
R5 3600 = 6 cores 3.6 GHz base 4.2 GHz boost clock (3500 ...
I've used the ASUS B450-F for my last Ubuntu build. It was originally a R7 1700x on an ASUS B350-F, then I later swapped it for a R7 2700x on an ASUS B450-F. No issues with either board.