Only if you happen to have the relevant skill set.
Speaking as someone capable of designing the mechanical hardware and who is broadly electrically savvy but who is most definitely not an embedded engineer: I could bang out a few hundred hacked together dev boards in week, but doing a custom board would take me a few months. Starting with reading 'Prototyping PCBs for Dummies'.
Also it's actually simpler than it might seem, especially if you are not doing anything high-power or high-frequency (which, again, if it's a bunch of breakout boards connected over 0.1inch headers they clearly aren't).
Watch a few YT videos, copy-paste the reference schematics for all those boards, delete what you don't use and you are almost done :)
Speaking as someone capable of designing the mechanical hardware and who is broadly electrically savvy but who is most definitely not an embedded engineer: I could bang out a few hundred hacked together dev boards in week, but doing a custom board would take me a few months. Starting with reading 'Prototyping PCBs for Dummies'.