I've created a similar discussion, but I'd like to say I have WebView disabled and have noticed no issues so far. I suspect the biggest functionality breakage would be accessing WAPs that use captive portals for signing in. Though, without any web services on your device anyways, that might might not be critical for you.
Apps that are granted the Network permission should still work. For example, Obtainium works for keeping my apps up to date and installing other apps. System updates as well as GOS app updates work fine as well.
These are just my observations! I am not an expert. Does anyone know of insecurities that may be introduced as a result of disabling webview?