No issues with battery life here.
I do have an always-on VPN, and about 20-30 apps installed.
Even the apps with unrestricted background usage don't seem to actually use much in the background: < 1% according to the battery usage in settings. That will probably depend on how the app is designed.
When I switched to GrapheneOS I did not notice any increase in battery usage compared to the stock Pixel OS.
I imagine it could vary a lot depending on the apps you have installed.