Ability to share via link the account with others so they can view data. This could be used to share with a financial advisor or with a forum (Bogleheads, Reddit, etc.) to get feedback.

Ability to share a single plan or the entire account.

Ability to set a timer on the share link (persists forever, good for 1 hour, good for 1 day, good for 1 week, 1 month, 1 year).

Share should be read-only but as a stretch goal it’d be nice for: 1. The recipient to be able to make changes to view the impact but not write those changes (the current Compare feature). 2. The recipient to be able to create a new plan based on the changes (rather than overwriting the existing plan… which might be its own nice enhancement to the Compare feature).