So, I can use the sfdx CLI command to get all the properties of an object using force:schema:sobject:describe -s OBJECT . However, this needs a fair bit of additional legwork to just get a list of fields. Is there a better command to use than the schema one?

From the excerpt below, I'd like to just get something like ['relationID', 'whoID']

{ actionOverrides: [],
  activateable: false,
  childRelationships: 
   [ { cascadeDelete: false,
       childSObject: 'AcceptedEventRelation',
       deprecatedAndHidden: false,
       field: 'RelationId',
       junctionIdListNames: [],
       junctionReferenceTo: [],
       relationshipName: 'AcceptedEventRelations',
       restrictedDelete: false },
     { cascadeDelete: true,
       childSObject: 'ActivityHistory',
       deprecatedAndHidden: false,
       field: 'WhoId',
       junctionIdListNames: [],
       junctionReferenceTo: [],
       relationshipName: 'ActivityHistories',
       restrictedDelete: false },

 

• I have SFDX CLI working.
• I can query SFDX from powershell if that is easier (and will if can't figure out an alternative).

Also, no DX category?

This is the trailhead challenge I'm working on.
Create a report of Opportunities grouped by Type. Then follow the dashboard and share a snapshot on Chatter.
Name the report 'Opportunities by Type' and save it to the 'Unfiled Public Reports' folder.
The report must be of type Opportunities.
The report format must be a Summary report.
The report must be grouped by 'Type'.
The date range should be for All Time.
You can include any columns you like, but must include 'Amount' as one of the columns.
Create a dashboard named 'Opportunities Dashboard' and save it to the 'My Personal Dashboards' folder.
Create a dashboard component on the dashboard using the report you just created.
Set the header to 'Opptys by Type' and the title to 'For all time' for the dashboard component.
Use the horizontal bar chart dashboard component, and ensure the record count is displayed on the x-axis.
Follow the 'Opportunities Dashboard' dashboard in Chatter. Make sure that Feed Tracking is enabled for Dashboards first.
Post a snapshot of the 'Opptys by Type' dashboard component to Dashboard Chatter feed.

But I'm getting the following error when I check if the challenge has been completed
Challenge Not yet complete... here's what's wrong: 
The dashboard snapshot post to Chatter was not found.
Can someone hepl me?
If possible post the snapshots?