I'm no expert but I think you're right, you probably want to keep the garage door matched closely to the brick around it so you don't highlight the garage. I think the bright white on the front door looks nice but maybe to make to stand out more a different color would be fun, but yeah, not red, lol! Ok, I'm no help but hopefully my comment will bump it up.

I think a navy blue would work really well - SW Naval, BM Hale Navy or - my vote - SW Sea Serpent: https://www.sherwin-williams.com/homeowners/color/find-and-explore-colors/paint-colors-by-family/SW7615-sea-serpent#%2F7615%2F%3Fs=coordinatingColors&p=PS0

So much of this depend on whether you want to make this look right….it is two obviously different sections… completely different windows…doors…and a ton of personality on the tiny side……pretty blah on the major portion …..every effort should be made to unify the curb appeal….it is my opinion that adding some cute to the big side is the way to go….for re- sale later on …and for your enjoyment every time you come home

Color is so subjective. In the close up pic, I really like the color, but in the wider shots all I can see is the zebra effect of the white with dark boards and the door just disappears because of it. Do you like the way the white portion looks? I'd be leery of adding a bright color to the door because it will compete with the stripes. If you like the striping, then what about a white door? Your gray is so neutral, you could use just about any color you want. Yellow always looks nice with gray but I don't think it's right for the style of your home: Maybe a brighter red?