When I switched to a new Pixel I tried using just VOIP without a SIM for a few days, using wifi only and in airplane mode. Well it's been over a year since then and I'm surprised I actually never needed a SIM. This may not work for most people, but given my location, I'm always in an area that has wi-fi available and all my traffic is routed through a VPN. The only time I don't have wifi is when I'm driving, but if there is a real emergency I can always call 911 without a SIM.
Alternatively, with my previous Pixel I had a pay-as-you-go SIM from a Sprint reseller purchased with cash from a Best Buy. I activated it online over a public wifi using a fake name and hotel address and paid online with a masked card and that setup worked well too.