Despite some suggestions to the contrary, Valve Index Controllers work fine with The Assembly--I played the game to completion (in September 2022). The controls are slightly unconventional by today's standards and aren't explained anywhere, so they initially required a bit of experimentation.

B: pause/menu
A: objectives; exit computer; exit microscope
Trigger: interact; move (teleport)
Left thumbstick: turn (90 or 180 degrees)
Right thumbstick: move (nudge); navigate through computers (emails, passwords); rotate microscope samples