Not sure how you manage the surplus or savings but i use the category tracker from: Docs: Category Tracker were on the top left it shows you the net income and expenses and cash flow. where one can see the amounts saved for a period by changing the start and end dates.
I generally use it to see what’s the actual expense, income, and net for a period and use something similar to a net worth sheet to see total assets overall.
But if you want to see the amounts encumbered for a trip you can try the sinking fund on [Show and Tell] Sinking Fund and Mega Savings Goal Tracker (YNAB-Style)