It does also have third party repos such as sbopkg. This does a bunch of the movement for you when installing packages though you still need to manually install dependencies, BUT If you also add sboui which is a front end package resolution for dependencies then the process is much faster. I like the stability of Slackware, and also because its helps me get better for when I try the BSD since its very much like them as well.
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.