@LarsArneson, @YosefBodovski1 -- It is possible to embed spreadsheets in stories. Make sure the spreadsheet is shared publicly and be sure to use the specific embed option the hosting service offers. In MS Excel this is under File > Share > Embed, and in Google Sheets it's in File > Share > Publish to web > Embed.
If you just use the regular link to embed a spreadsheet your readers will see all the spreadsheet editing tools, which is overkill and adds a lot of unneeded noise to your story (I think this is what Bern was getting at with his comments). The embed options provide a focused view that's more appropriate for viewing; however, it still might not be ideal since the table might not fill the embed frame the way you expect.
Here's an example of a Google Sheet embedded in a story:
We do also recognize there is a need to present simple tabular information in StoryMaps in an accessible way that matches the theme of your story. In fact, we are currently working on adding the ability to create simple tables in a story. This feature is planned for release in Q3 of this year.
Here's a sneak peek of a mockup of the design. This is subject to change since it's still in development, but we're planning to support tables with up to 10 columns and 50 rows. The tables will be themed to match your story, will be accessible for readers using assistive technologies, and will also work well and look good on small screens.
Let us know if you have any thoughts on this upcoming feature.
Owen Evans
Lead Product Engineer | StoryMaps