I have finally found an easy yet permanent fix for the headset play issue when using the separate handlebar/stem combo. Please bare with me as I'll do my best to be clear and concise. You do not need an FSA ACR setup, nor disconnect any hydraulic or shift cables.

Hello,
last year I built my first gravel bike velobuild GF-002, had some issues, most of them were due to my lack of enough experience and very easy to solve, and some were known velobuild issues, still relatively easy to solve.

I rode my bike over 3500 km.
My friends, after seeing me riding with confidence, also wanted to have a gravel bike like that, so I built another 7 GF-002 for friends, with integrated bar and separated bar and stem combinations, during that process, I learned lots of tricks, and made my tools better and collect a good amount of experience for building bikes.

I thought now it's time to build a proper road bike for myself again, and here it is, my new VB-R-177, and I absolutely love it.

The classic headset play problem can be solved (at least in my cases) with a sand paper, you should sand the steerer tube until the headcap sits perfectly on the compression plug, and yes, it should be straight, so take your time and try to have a clean cut, it helps.
If you still have problem, micro shims are your friend, cut one and put it between compression ring and headset cover.
For another classic problem, rubbing brakes, you should use M5 bolts that comes usually with break rotors(for 6 bolt rotors) as they are a bit shorter than regular bolts, they may help a lot to adjust the breaks properly.
Other than that, I don't see any major issue on velobuild side.

If you are considering some semi-hydraulic solution like juin-techs, you should not, yes, they can stop you, but the difference is like day and night, now I feel much much safer on descends, and have much better control overall.

For internal cable routing in handlebars, after testing the new method on a friends bike and saw the results, I did it for myself too, so here is how: just escape it, as easy as that you save yourself a good amount of time, and it gives you the possibility to change, bar or stem in future if you want to, I will post a picture so you can see what I did.

After about 200 km on this, I can say the ride quality is very good, the bike is very responsive, climbing and descending is very fun, the bike is fast and comfortable.

I did not build a weight weenie bike, so my setup with pedals, bottle cages, garmin mount and velobuild gravel wheels (which I used on my gravel bike) is 7.9, so you can cut some good amount of weight if you go for a lighter wheelset.