Ironically, the Pixels are the only devices officially supported by GrapheneOS at this time. If you ever get sick of google enshittification this is definitely something to look into

This happens to my wife where she’ll get a voicemail a month late. Idk if it is a phone problem or a network problem

I do feel like I have also had that experience, but I suspect it's because I nearly always have my phone on silent and otherwise use Signal. But notifications do arrive inconsistently late! I wonder if that is connected to battery saver or something. Definitely a worthy criticism, though; thanks for bringing it up.