Neoniq For many users, 2G and 3G are already shut down or in the process of that happening. It's going to happen everywhere eventually. VoLTE is required for calls on 4G (LTE) and VoNR is required for calls on 5G (NR). This is why we added the toggles for forcing VoLTE, VoNR and 5G as a high priority. GrapheneOS is used more internationally than stock OS Pixels support well so we've provided this for people using GrapheneOS in countries with poor stock OS Pixel support. We're NOT going to change the defaults from matching the stock Pixel OS since that provides the best overall stability and compatibility. If users want or need VoLTE, VoNR or 5G they can now force enable it even though the stock Pixel OS would not support it. It may be disabled with a carrier for a reason such as a poor or incompatible implementation on their end. In countries where Pixels are not officially sold, the configurations are generally just half-baked because they're not heavily testing it and they want to test features properly before enabling them.
You might as well force enable it if you know it works and are going to remember you did that in case you ever experience an issue with it. If you want, you can use our added 4G-only or 4G/5G-only mode to disable 2G/3G. Overall, 4G-only mode will provide the highest security and least power usage by not having 2G, 3G or 5G being used. In the future, 5G-only mode which requires support for standalone (SA) 5G as opposed to non-standalone (NSA) will become more useful once 5G is more power efficient and battle hardened. In many parts of the world.