It definitely is, that's kind of the only downside to it

If you ever reset your network settings, you lose your eSIM. You then have to go to their showrooms to get it back.

I have an iPhone 13 which does have both slots yeah

Damn found this post at a perfect time. I just got my Jio eSIM done an hour ago. For context, my phone was from Dubai, so I can explain the process.

1. You can port your current number easily, don't worry about it.
2. It will not cause an issue, however make sure that you mention this fact to them.

Go to a Jio showroom to get this done. In my case, we forgot to tell them that my phone is from Dubai so the process failed and we had to go back there to do it again. They will have to do something called bKYC (Branch KYC), so make sure you mention that your phone is not from India.