I went through a similar dilemma when I got more into road riding during the pandemic. My bike originally came with an 11-speed 11-32 cassette with a 50/34 crankset, and I just was not comfortable with the gaps in this cassette. Like you, I was always hunting for an in-between gear on relatively flat terrain. So I swapped from 11-32 to 11-28 to 12-25 to 12-28. In the process, I became a gearing expert, reflecting my narrow power band (otherwise known as cadence intolerance here on Bike Forums).
In your case, comparing (A) a 10-speed 11-32 cassette to (B) an 11-speed 11-28 cassette, both driven by a 50/34 crankset:
Bicycle Gear Calculator (gear-calculator.com)
Assume that you cannot use the 3 or 4 physically smallest cogs of the cassette with the 34T chain ring, then compare the respective gaps between the two drivetrains, especially at higher velocities. (A) has many more gaps than (B). On (B), the only significant gap for most people is the 17T to 15T gap in the cassette when on the 50T chain ring.
However, as you are considering a whole new bike (rather than just buying a new cassette), just buy the bike you want with the crankset you want, then swap the cassette later if necessary. In other words, do not let the installed cassette deter you from the bike you want.