Man, messaging is a nightmare. I use signal with a few of my closest contacts, whatsapp with most other people, sms as a fallback and for work I have to occasionally use Teams and fucking Viber (ugh). At least I managed to liberate myself from the clutches of Slack.
If only there was some standard way to get these apps to talk to each other so everybody could use what they want. Oh wait, there was, it was called XMPP, it worked perfectly and big tech fucking killed it and replaced it with the irritating clusterfuck that is the current status quo.
Luckily they don't have to switch. Your good friends from the European union have a solution for you (And the latest beta for whatsapp features the skeleton for their implementation of that standard)