A couple of years after Google Voice split out from Hangouts and, while there were plenty of VOIP options, they all sucked for use as a personal number (even Google Voice kind of did to be honest). The latencies for ringing, not being accepted at ever more places, the weird connection quality and delay issues, one way audio issues, and so on were just so rampant compared to a "traditional" (now also really just data, but more integrated into the transport system) number. Also so many places started to block the use of VOIP numbers it was becoming hard to use the number anyways. If they hadn't already there was no guarantee it'd still be a valid option 3 months later. Maybe there is some whizz bang new VOIP service that actually kicks ass in all of these marks and someone will recommend it but even if they did I'd have more expectation it's a false positive report than a real positive.
If privacy/secrecy via obfuscation is your #1 criteria and not a nice to have then I'd just go with an enterprise cloud VOIP solution like RingCentral because they'll have real support and it's their core (and very successful) business, not another something that'll disappear in 2 years anyways.
If privacy/secrecy via obfuscation was just a nice to have and you really liked it for having the web interface then RingCentral (and I'm sure others) have a PWA and you can still go that route or you can try a sync tool like Beeper. I went the latter route as it gave a significantly better call/texting delay and quality experience to give up the obfuscation but the other cost is your phone has to be connected to the internet for the messages to relay through Beeper.