Essentially something similar to wealthfront’s retirement tracker that can help user estimate whether they are on track to retire by a certain age the user desires. This can be based on current trends/budgets and what the user expects to spend per month in retirement. Unlike wealthfront, user should be able to determine which accounts are considered. 

If possible perhaps also allow the user to be able to adjust various parameters such as life expectancy, estimated social security benefits, future housing costs, other anticipated expenses, and average inflation rate to fine-tune their retirement estimation

Ex:

https://images.app.goo.gl/NYAkR2zmNjbz4sbm7