Googlebooks can't install the Slack web app on day one

Googlebook is now shipping, but on day one users cannot install the Slack web app as a PWA — it returns a "this app cannot be installed" error. Google points users to Slack on the web, but only a Chrome tab shortcut works, not a standalone window. Other PWAs like Photopea, Squoosh, and SnapDrop work fine.

• Slack web app fails to install as a PWA on Googlebook on day one
• Only a Chrome tab shortcut works, not a standalone window
• Play Store banner says Slack is "better on the website" than the Android app
• Photopea, Squoosh and SnapDrop PWAs work normally on Googlebook