If you are interested in crossbow + traps build, then I suggest something similar to this:
https://underrail.info/build/?HgMHBwMQAwcAVcKgAADCoMKgPygAMlxwO0paAAAAAE0AOgF_IhkwwoA4M0xLaiYCMcK1wqQabcOcw4LCncKewp_CreKjsQXip74K378Quick Tinkering allows to put traps on the battlefield during combat, while Deadly Snares gives you 100% crit chance against enemies stuck in bear traps or acid blob traps.
Aimed Shot is skippable but it is quite helpful in early game and unlocks Sharpshooter later on which boost damage of your crits
You can keep Grenadier if you want but later in the game you want to mostly use special bolts like acid, incendiary and shock and they occupy same utility slots as grenades.
In regards to items, most important is Bolt Quiver belt which reduces AP cost of crossbow attacks. For crossbow model, most optimal is Cyclon with Pneumatic Reloader and Anatomically-Aware Scope (green scope). It has lowest AP cost of all models so with quiver it allows you one more attack in a turn. On your head wear Night Vision Seeker Goggles, to boost crit chance and negate darkness penalty
80 effective chemistry allows to craft corrosive and rusting acid bolts
Around 115 effective mechanics and 140 electronics with crafting benches bonus later on should allow crafting any type of endgame crossbows and energy shields.
100 effective biology shoul allow to craft and extract almost everything, but you can lower it to 80 and put the points in chemistry instead (there is one merchant later who unlocks corrosive acid for sale if you pass 100 chemistry check and 80 biology is enough to extract rusting acid from sea wyrm glands)
