Grackle for Google Docs

With Grackle Docs, you get

Feature Description
Accessibility Checks: 22 accessibility checks against WCAG 2.0 and PDF/UA standards, including…
PDF Output: Unlimited conversions to Tagged PDF(/UA). Important when creating documents to be shared outside of G Suite.
Change Reading Order: This changes the internal reading order for PDF documents without changing the physical appearance.
Table Tagging: Awesome, built in wizard makes tables a cinch.
Set Specific Checks on/off: We check for 22 accessibility standards by default and this gives you the ability to change the number of checks if some are not required for your needs.
Set Document Properties: You can add information to the properties of a PDF file created.

Grackle for Google Sheets

With Grackle Sheets, you get

Feature Description
Accessibility Checks: 13 checks against accessibility standards, including…
HTML Output: Unlimited conversions to Accessible HTML.
Auto Table Detection: The Add-on will automatically define individual tables within sheets.
Table Structure: The Table Structure tab will show you the complete Sheet in a tree like structure.
Table Naming: Ability to name individual tables within each sheet.
Table Re-ordering: Move each table to the desired position within the Accessible HTML output.

Grackle for Google Slides

With Grackle Slides, you get

Feature Description
Accessibility Checks: 16 checks against accessibility standards, including…
Unique Title: Each Slide title should be unique.
Multiple Title: Each Slide should have one title only.
Empty Slide: Slides should not be empty.
Table Tagging: Awesome, built in wizard makes tables a cinch.
Contrast: Text will be checked against background for color contrast