Self install for a 24' AGP. I ran two 120V, 20A dedicated circuits out to a pole 6' from the pool wall. One will be for a 120V GFCI convenience receptacle fed from a standard 20A circuit breaker. For the pump, I purchased a 20A GFCI, single pole circuit braker that snaps into the neutral bus bar (no neutral pigtail) but it will not fit into my SquareD homeline panel. The "blades" on the back of the breaker are narrower that what my panel has. It's a 20+ year old panel so perhaps SquareD made some changes throughout the years.
Instead of trying the breaker with neutral pigtail, could I wire a faceless 20A GFCI in-line prior to the pump service switch?

Square D Homeline 20 Amp Single-Pole Plug-On Neutral Dual Function (CAFCI and GFCI) Circuit Breaker HOM120PDFC - The Home Depot
Bring essential protection to your homes circuit system with the selection of this excellent Square D Homeline SinglePole PlugOn Neutral Dual Function Circuit Breaker.
www.homedepot.com
Instead of trying the breaker with neutral pigtail, could I wire a faceless 20A GFCI in-line prior to the pump service switch?