Place the cream cheese and cream in a small bowl and stir until combined. Place Old Bay and Sichuan pepper in a separate small bowl and mix to combine. Melt 1⁄4 cup butter in a small pan over low heat, then add garlic and cook until soft and fragrant but not browned, about 5 minutes. Remove from heat and let cool. In a medium bowl, whisk cream-cheese mixture and garlic butter until fully combined and smooth. Melt the remaining butter over low heat and set aside.
If using king crab legs, carefully remove from shell in whole pieces as much as possible. Cut crab into four 4-in.-long pieces. Place 1 lumpia wrapper on a dry surface. Place 1 crab leg piece, or 1⁄4 of the lump crab, on bottom third of wrapper and season with salt. Drizzle a little of the melted butter over crab and brush egg wash on edges of wrapper. Tuck both sides in and roll into a long cigar shape. Repeat with remaining crab and wrappers. Place rolls on a pan or plate lined with parchment paper and place in freezer to chill, about 15 minutes.
Place oil in a large deep-sided pot, making sure it doesn’t reach more than halfway up the sides. Heat oil to 375° over medium heat. Remove crab rolls from freezer and gently lower into oil, frying two at a time, until light golden brown, about 5 minutes. Drain on paper towels. Cut rolls in half on the diagonal, sprinkle with spice mixture, and serve with garlic–cream cheese sauce on the side.