As already seen by various other posts, such as 8, Vista, and XP, there have been unofficial ways of getting support. If this is the case, would that mean we could install updates from Windows Embedded 7 or Windows Thin PC (both based on 7, but have longer EOL times, up to 12th October 2021), in a similar way that Server 2008 or POSReady 2009 provided updates to Vista and XP respectively?

Windows 7 still get updates via ESU program which is paid, not free.

If you know the kb numbers, you can get updates for the Embedded SKUs from the Update Catalog:

https://www.catalog.update.microsoft.com/Home.aspx

IDK if they will install to the retail OS, I haven't had the need to install an update in awhile.

2 hours ago, Tripredacus said:

IDK if they will install to the retail OS, I haven't had the need to install an update in awhile.

This will not work, the system verifying that there is a valid ESU key, as well as other prerequisites :

 

 

Is that for all updates or just the ESU Licensing Preparation Package?

All security and cumulative updates released after January 14, 2020 require an ESU key to install on a classic Windows 7. Except the Licensing Preparation Package and SSUs.