I don’t think it really should be a problem. I have not done this, but it seems like (depending on who your carrier is) that it should be easy to move the eSIM from iPhone 1 to iPhone 2. I’m not sure the steps the OP would need to take if iPhone 2 has a physical SIM and does not support eSIM.
For example, I have a 15 Pro (on IUP) and SE 3 that I use for work. In settings, under cellular, I have the option to move my number from the 15 Pro to the SE 3. I haven’t done this before since I don’t have a need to swap/move eSIM, but if my 15 Pro was damaged beyond being able to use, I suspect it would be seamless to move my phone number to the SE 3.