Based on what I’m finding in “best Google Home Skills” articles, the “store” can only be accessed from mobile:

https://beebom.com/best-google-assistant-skills-actions/

> Just long press on the home button to summon the Google Assistant and then tap on the button at the top-right corner. That should take you to the “Explore” page where you can explore all the skills and actions that Google Assistant has to offer you, categorised into various handy categories.

https://lifehacker.com/the-best-google-assistant-skills-to-u...

> you can find a list in the Google Home app. To find it, tap the menu button in the top left corner, tap “More settings” and then “Services.” Here you’ll find a list of services you can try. Tap one of them to get a description and some sample commands you can use.