> Now we need to create a new operating system for an optimal user experience.
No we do not.
TLDR: Choose Pop!_OS or ElementaryOS as they both match the 'It just works' requirement for all users.
Since you are targeting developers, it already indicates to me that you build on top of Linux which meets the drivers requirement to support the laptop's hardware. Linux already has the majority of the developer mind-share, so I see no reason to use a BSD for the desktop in this particular use-case. Don't even think about rolling your own distro unless you have a good reason to or you can afford to maintain it.
Now, the real question is: Which distro to choose for developers for optimal user experience?
To help you choose such a distro, there has to be one that must offer a level of customization that doesn't sacrifice the consistency of the OS with standard defaults to revert back to via both a CLI or GUI settings control (As found in macOS and Windows). Another requirement is having a distro that has software that feels integrated with the system software and it behaves predictably such as desktop keybinding software must work across all windows and apps or the availability of accessibility software built-in such as text-to-speech. Following this, you have eliminated 70% of all Linux distros that fail this.
Also, this distro needs an easy and consistent way of installing development libraries or even the latest libraries without it getting in the way of the developer's work. Whether if it breaks the OS or forces the developer to decipher those cryptic error messages via googlgling for each distro / library combination. Well done, you have eliminated some of the default Linux desktop OSes that do just that.
Lastly, what happens when a dev tries to install your software / firmware update? Is it as clean as a Apple software update? Is there a easy way to revert a failed system update without reinstalling the entire OS or trawling through a blog to copy-paste commands for recovery options?
Unfortunately, every Linux distro requires the latter and there is no standard or easy way of rolling back a bad update without typing a few commands. If we have users that do not mind this issue, then a choice of either Pop!_OS or ElementaryOS look like clear winners to me to pre-install onto a standard or high-spec laptop to sell to devs and consumers.