Is there a limit to how many equips you can attach to a single unit at the same time?

No, there is no limit to the number of equipment cards that can be attached to a single unit at the same time.

According to Rule 744.3.b, a unit is considered "Equipped" as long as one or more of its attached cards are Equipment. There is no rule in the game that restricts the number of attachments a unit can have.

As long as you have the resources to pay the equip costs and the equipment is not already attached (as you cannot activate the equip ability of an already attached piece of gear, per Rule 730), you may attach multiple pieces of equipment to the same unit.