Many years ago I tried that, and found out that privacy is possible, but the cost is incredibly high.

By using pi-hole I was able to find out if my mobile phone was communicating with Google. As long as I had GAPPS on LineageOS, there was plenty of traffic. When I removed GAPPS, the traffic went quiet, but my phone became severely crippled.

Sure, I still had some smart apps on my smartphone, but I was also cut off from my bank, so basically living without money in todays society. Not really a viable option. Also, updating apps from fdroid was incredibly inconvenient, but I hope that issue has been fixed now.