Just brewed my first pumpkin beer, a lager with an oktoberfest base. Just added 2 pounds of canned pumpkin (unspiced) to the mash and added pumpkin pie spice in secondary (used the spice combination from Brewing Classic Styles). Just over a week in the bottle and it tastes fantastic. IMO, the oktoberfest is a perfect base beer for a pumpkin beer with the malt character, color, etc
I know this does not address the question of commercial pumpkin lager, but hopefully helps you in your quest to make your own pumpkin lager.