I've done almost all of it piecing together other people's advice.
On your primary report data source:
Create a column with the hyperlink for the detail page. Set its data category to web url
On your primary report:
For the table column that you want to behave like a hyperlink, use the conditional formatting menu to assign it the web url column you created in the previous step.
source: https://docs.microsoft.com/en-us/power-bi/create-reports/power-bi-hyperlinks-in-tables
On your detail report:
Add an object (shape, image, etc) that you want to behave like a back button.
On that object's format > action menu, set action to On, type to Web URL, and paste in the URL of where your main report will be posted.
Bonus round: Pass parameters to the detail page using the URL
My use case is a KPI dashboard where the current values for all the KPIs show on a table on the main report, and then you click into the detail page. I could not use the drill through feature because it depends on a right click. Screen readers do not have a right click capability. My ADA compliance publication guideline requires all data and navigation to be available to screen readers.
source: https://docs.microsoft.com/en-us/power-bi/collaborate-share/service-url-filters
Primary downside to this approach:
Each click spawns a new tab. So if I start at the primary report, click the detail page and go back, that is 3 tabs. That is a browser setting that I cannot override from Power BI. I might write some javascript to clean that up, maybe to intercept the URL with the parameters and replace it with an iframe on the same page or some other magic. Not thought it through yet.
