Use the inspect command to show updates that can be applied to a solution.
Inspect the current folder:
cd C:\code\MyApp nukeeper inspect
This produces output e.g.
Found 2 package updates Microsoft.Extensions.Configuration.Json to 2.1.0 from 2.0.2 in 1 place since 13 days ago. Swashbuckle.AspNetCore to 2.5.0 from 2.4.0 in 1 place since 6 days ago.
You can inspect a different folder:
nukeeper inspect C:\code\MyApp