Q:

Can you set Google Play and Android OS updates to specific WiFi only? 

I know I can set my phone to update only on WiFi.  But can I set it to update only when connected to a specific WiFi?  E.g. update only when connected to Home WiFi or Office WiFi.  This is both for Android system updates as well as App updates via Google Play.  
What I specifically want to avoid is to trigger updates while using a 4G hotspot.  
If it matters: Android 6.0

A:

This isn't quite what you describe, but recent versions of Android let you designate some Wi-Fi networks as "metered".  Those Wi-Fi networks will count as mobile data for the purpose of the data restrictions in the main settings, and for Wi-Fi vs. mobile data settings within each app.  Therefore, if you set the 4G hotspot's network as metered, any app you have set to update, download, or sync only on Wi-Fi won't use that network. 
From the main settings, go to Data usage, then in the three-dots menu, select Network restrictions.  Find the 4G hotspot you're concerned about, and turn its switch on.  Note that only networks you've previously connected to appear in this list, so you'll have to connect to the 4G hotspot before you can do this, and hope that nothing updates while you're navigating the settings.