The whole point is that it's unusable without Google services due to battery drain. Meta got it right with WhatsApp and a battery-efficient WebSockets implementation for notifications without Google services, but Signal's implementation is poor.

This is an exaggerated take. I've been running Signal on LineageOS for years across at least 5 different phones in exactly this manner with no Google services installed. I'm currently using a Motorola G84 and charge every 2 days with moderate usage; Signal is my primary communication method with family.