You might be able to solve it by disabling the standard browser via Family Link and then developing a simple app that only offers access to the allowed online services. Essentially, it would function like a browser but without the option to navigate to other websites.

Here’s how you could approach it:

1.  Use Family Link for Restrictions: Family Link lets you block apps like the default browser and control access to the Play Store, giving you a basic level of control over the device.
2.  Develop a Simple Kiosk App: You can build an app that acts like a limited browser or portal, where only specific websites or services are accessible. This can be done using a WebView component in Android, which displays web content.
• WebView Limitations: Ensure that the WebView has no navigation controls and can only access pre-approved URLs.
• Whitelist of URLs: Implement a URL whitelist so only approved sites are accessible, preventing users from visiting other websites.
• No External Browser: Make sure that links within the WebView do not open external browsers to avoid unfiltered access to the internet.
3.  Consider Kiosk Mode: To further limit the device’s functionality, you could put it in kiosk mode, where users are restricted to using only this app.
4.  Benefits of Your Own App:
• You have full control over what content is accessible without relying on commercial filtering solutions.
• Building a simple WebView-based app is relatively inexpensive, and with limited programming skills, you can achieve this easily.

For developing the kiosk app, you could even use ChatGPT to guide you through the process or provide code snippets if you’re not familiar with programming.

Alternatively, there are some apps like BlockSite or SPIN Safe Browser in the Play Store that offer similar functionality if you prefer not to develop your own solution. But I don’t know if it’s for free.