While it's not possibly to directly pull potential reach data from Smarp into Supermetrics, you can use a simple formula to create the same results in your reporting.
Only LinkedIn and Twitter provide connection counts, so these are the only 2 data sources that you can calculate this metric for.
Example
If Andy has 500 connections on LinkedIn and he made 3 shares to LinkedIn during November 2021, his potential reach is 500 connections x 3 shares, so 1,500 potential impressions.
Instructions
To calculate potential reach through Smarp, multiply the number of connections on a specific network for a specific user by the number of shares that the user performs on that network. Define a timeframe.