Yes, it is possible, though fairly prohibitive. You can get modules for connecting a Sim card to your laptop to make and receive calls and SMS, so all the third party authentication messages and calls can be done. Apps can often be run through an emulation layer for Android, not so much for iOS, but yeah, it can mostly be done.
That said, there are devices like the Pinephone which run a mainline Linux distribution like Arch or Alpine and can also do calls, SMS, and if you are brave use some android apps. If you can use a Pinephone for it then you can use another Linux laptop with a phone module to handle everything else.
I am much more worried about things like banking now. A bank that allows use of an app on your phone with NFC is great but when they take away using anything else I would become a little more worried. If they can keep an option open, say having standard cards along side phone NFC, then the lock in is much less profound. If we get to a point where they cannot operate without Google or Apple giving the go ahead then they cannot move away if things get bad, so those monopolistic companies can extract more value from those banks and that gets passed down. This applies to tonnes of other services like taxis, food delivery, booking doctors appointments, and so on.
First, start big. Get the basic shapes right with large lettering. Ideally you would have something you are comparing to like a stencil or grey printout so you can see the difference between your writing and the target.
After you have the shape fairly good large you can shrink it down. You can take your time getting to that and just make a little progress at a time.
If you find it impossible to shed your current handwriting consider using grid paper to force spacing and maybe try your non-dominant hand.