Macerate the berries: Toss sliced strawberries with granulated sugar and lemon juice in a medium bowl. Let sit at room temperature for at least 30 minutes, stirring once or twice, until a deep red syrup forms.
Make the cheesecake mousse: In a large bowl, beat softened cream cheese and powdered sugar until smooth, about 2 minutes. Beat in vanilla. In a separate clean bowl, whip cold heavy cream to stiff peaks. Gently fold whipped cream into cream cheese mixture in three additions using a rubber spatula until fully combined and light.
Prep the cake: Cut pound cake into 1-inch cubes. (Optional: spread on a baking sheet and toast at 350°F for 5-7 minutes, then cool completely.)
First layer: Arrange half of the cake cubes in an even layer at the bottom of your trifle bowl.
Second layer: Spoon half of the macerated strawberries and their syrup evenly over the cake cubes. Let sit for a minute.
Third layer: Spread half of the cheesecake mousse gently over the berries. Smooth to the edges with an offset spatula or spoon.
Repeat layers with remaining cake cubes, remaining berries and syrup, and remaining mousse. Smooth the top.
Chill: Cover with plastic wrap and refrigerate for at least 3 hours, or overnight, before serving. Garnish with fresh strawberry slices or mint if desired.