That's not even haha, that's like 6/10 likely.
For historical (and arguably even political) reasons, federal courts give the states a bit more leeway when to adult content. But regulating general purpose content-neutral VPNs would really be stepping directly into the FCC’s domain, in a way which would directly impact interstate commerce, and I doubt the courts would let them do that
I could legit see them investing insane dollars on this project.
I don't think this is federally illegal either
If the FCC wanted to overrule it, they could, and the Courts would likely be on the FCC's side. See https://crsreports.congress.gov/product/pdf/R/R46736
But I doubt it would ever get that far. It would be a huge burden on every large corporation operating in Texas, if interstate traffic had to go through some legally mandatory firewall or content filter. The Texas state legislature is generally pro-business, and if almost every major corporation in Texas would be lobbying them not to do something, I doubt they'll do it. And, in the very unlikely event the legislature ignored that lobbying and did it anyway, and the Governor didn't veto it – then those corporations would likely go straight to petitioning the FCC, and I think it is likely they'd succeed in convincing the FCC in overruling it.