For anyone comfortable with some basic coding, you can install this script which will force Google Calendar to refresh/sync with Outlook at a more frequent interval. I believe by default, using the 'Add Calender -> From URL', it only refreshes every 12/24 hours.
Installing the script just involves copying and pasting a few files. Set-up just involves editing the appropriate fields with the Outlook .ics url, and changing the interval for the refresh timer. More details can be found here:
https://github.com/derekantrican/GAS-ICS-Sync?tab=readme-ov-file
A little more complex to set-up than the other share/publish calendar solutions I've seen, but allows for a more frequent sync rate.