No, that isn’t necessary. You have two options:
One device for everyone. You can share a single phone or tablet and simply
pass it on. Each child switches to their own profile and sees only their own tasks.
Then the device moves on to the next one.
A device of their own. If your child already has one, that’s of course the
most convenient. No SIM card is needed – Wi-Fi is perfectly enough, and an old family
phone does the job just as well as a tablet.
Either works. Where a child does use their own device, they experience it not as
something purely for consuming but as something they use responsibly for what counts
in real life. That builds digital literacy along the way.