Earlier quoted context omitted.
One time, I needed this. I lost my phone with a physical SIM card and needed a replacement that day. Now I'm trying to remember the eSIM transfer flow to know if this is still an issue. But also, which MVNO should you go to? Carriers supposedly prioritize their own customers, so it feels a bit like running on spot instances.
Personally switched from VZW to Google Fi. It's on TMOs network. As you can imagine, when engaging with Google's support was hilarious when there was something I needed, but overall I don't miss Verizon and pay drastically less.
I ended up switching to Mobile-X since I'm on wifi so much I only use a few gigs of data a month. $2/month + $1.90/GB vs Google Fi's flexible plan of $20/month + $10/GB.