Lockdown mode was released as a countermeasure specifically against Pegasus the first time it made the rounds as it disables many ways that are commonly exploited as the initial vector point - mainly attachments, links and previews in texts, as well as certain complex web browsing technologies.
I’ve had Lockdown mode on since it’s been released. I miss having 2FA code autofilled from text messages, and there’s the occasional website that’ll need to be whitelisted as it may display an emoji instead of a custom font… but aside from that, it’s barely an inconvenience.
Your telco is always going to be a weak point in a scenario like this, but better that than your phone because a hostile actor sent you a text message that embedded silent persistent spyware.
My only complaint about BCU is that its portable edition isn’t a single standalone EXE. Makes it a nuisance compared to HiBit Uninstaller.