This article mostly doesn't apply to the US market. Let me explain. There's two kinds of lock-in possible with eSIM devices. The first is the standard carrier subsidy lock that AT&T and T-Mobile do with phones sold through them. Verizon doesn't do this due to the old agreement to buy Band 13 spectrum. This is what most people understand, and while it's pretty easy to just ask to have the phone unlocked by the carrier, most won't do this.

The other kind of lock-in AT&T and Verizon do, but T-Mobile does not. This is relating specifically to ESIM (euicc) and it being paired to 'approved' IMEI numbers. AT&T runs IMEI whitelists that only allow devices they sell to be used on the network and these lists also contain what technologies it's allowed to access. Verizon has an approved device list, but I believe their physical SIM cards will work in any phone with band support and voLTE profiles available, much better situation since they've gone CDMAless. What they will not allow for eSIM is activation using just the EID number of the ESIM itself. They maintain a database of devices with eSIM and what the matching IMEI is supposed to be. If you have a device not in that list, it won't activate. The standard explicitly mentions that collecting the IMEI is optional for activation: https://www.gsma.com/esim/wp-content/uploads/2021/07/SGP.22-... (page 115)

I have a device called an esim.me. They are kind of expensive but it will give you support for up to eSIM profiles on a removable card (like an 'normal' SIM card, but it's a smartcard that supports flipping through these profiles). In the US it's only currently possible to activate these using T-Mobile, and unless you use an eSIM iphone or a specific model of Samsung phone, you have to call support and give them the EID number to activate it. I can then physically swap this 'esim' between my devices, anything that supports USIM (basically 3G and later devices, even old featurephone from 2007 it works in).