You wire a surge protector to its own set of breakers, never in parallel with anything connected to a breaker. You don’t need to or want to waste money on wiring it to GFCI breakers; you wire the SPD to regular 20A breakers. The SPD has two hot wires (black), a neutral wire (white), and a ground (green). Each hot wire gets its own 20A breaker (so that each leg of the panel is protected) and the white & ground are wired to their respective bus bars. This means the SPD will eat up two breaker slots on your panel. Mount and wire the SPD to the closet punch-out near the breaker bus and cut the wire sizes to an exact fit. You do not want to coil up any extra length of wire.
OK, makes sense. So needs a dedicated 220 20A breaker (or 2 110 20A breakers) at top of panel, before the IntelliFlo GFCI Breaker and others. Wasn't quite getting that from other posts nor the SquareD instructions and something just didn't seem right. Suspect the chatter I was reading was because others weren't using a dedicated breaker.