I would have suggested silent.link , while you can get a number not tied to your identity via esim, the main focus of numbers is a receiver for text and calls(also because it avoid people creating spam phone calls/txt). Which was originally for 2fa that only had cell # as an option. Also a number requires the user to be vigilant in paying their annual for it or they can lose the number. Also I think they can only cater for users in US, Canada and maybe UK.
ESIM using silent.link = a phone line that can only be used to receive messages and calls no outbound calls allowed. However you need a phone with esim support.
Physical sim on another device: great but you need a seperate hardware and have something extra to carry and charge.
Physical sim on a dual sim phone. Easier to carry however it runs the battery faster and sometimes you can forget which sim you are on if you are quickly calling or texting.
Mains sim plus VoIP line example is mysudo- use one phone, seperate your communication between your actual number and an app with VoIP. Seperate phones # via software since VoIP is all on app side. Requires you have an internet connection to work properly. Not all services are happy using VoIP and stop you from registering or changing numbers to VoIP.
Lots to think about, best of luck.