One thing I do to exert some control is use WHOIS to find out who their domain name and web hosting providers are and forward them the phishing texts. I've gotten multiple domains revoked through this process (though I've also been ghosted plenty).
Doesn't help if there are no domains linked, and I'd still love to attack their SMS instead because I suspect that's harder to replace.
In a similar vein I've had success surprisingly often when reporting spam email domains to the hosting company and Google safe browsing, which gives a big red warning page when someone tries to access the site (in Firefox and Chrome at least).
Wait, are you reporting those sites to Google safe browsing because of malware or phishing content? If so, great. But if they're just a source of spam I don't think you're supposed to be doing that.
I call the spam texts (hi Bob, it's Alice, we met last night type) and it's usually a Google voice number that want you to sign up for their whats app channel. I now text back them that we met last night and they can join my crypto investing WhatsApp group and I've gotten a lot less sms spam as a result. Must be on their black list now
Been getting spam texts out the wazoo and have felt powerless to do anything about it beyond delete them