Edit: someones already mentioned these below… nevermind!
If youre in the EU then EU parliament forced whatsapp to start developing cross-app communications with Signal, telegram etc. (Source). This was in 2022 and was due to be released in March 2024. Im not sure where it got to though since i dont use whatsapp, though i might start asking some friends to see if its rolled out.
Alternatively there are “matrix bridges”. Namely via Matrix which can link messaging apps through matrix accounts and send messages between
Crowdsec?