In a saucepan over low or medium-low heat, combine the large vegan marshmallows, pure pumpkin, cinnamon, pumpkin pie spice, and salt. Stirring very frequently, let it melt and mix together until it’s smooth and combined.
Transfer the hot pumpkin mixture into a mixing bowl and let it cool down to room temperature. This should take about 30 minutes or more if needed.
Once cooled, add the carton of thawed Cool Whip to the pumpkin mixture. Stir together until completely combined and much lighter in color, creating a fluffy filling.
Pour the pumpkin pie filling inside the graham cracker crust and spread it out evenly using a spatula.
Cover the pie with its enclosed lid from the crust and refrigerate it for at least 8 hours to thicken up and come together nicely. For best results, refrigerate overnight.
When ready to serve, top your vegan marshmallows pie with whipped cream and slice!