FORTH & HP: where to start?

[floppy]

Hello,
I was discussing with a family member and asked for a FORTH calculator based on Arduino since I have interest (on my 100+ project list).
But it could become a longer project.
So, has anybody any recommendation where to start with FORTH from scratch? (I will not wait for the project but could use an existing calculator).
a) what are the FORTH similar HP calculator?
b) is an HP50 with FORTH a good start? (I could see an announcement it has a FORTH module which can be implemented). I have no HP50: I should invest.
b) the HP71B with FORTH would be a quick easy solution? (I have an HP71B and never tried FORTH)
any recommendation where/how to start is more than welcome = advice what calculator would be the best for
- editing,
- storing programs on USB/virtual drive,
- what debugging method should be used
.. finally similar advices like here for HP41 debugging https://www.hpmuseum.org/forum/thread-19806.html