lucaschessR VS pinata

If you are looking for a weaker opponent (Stockfish 14, even at depth 1 isn't a walk in the park for a start) I did a little tournament between a bunch of not-top engines and found that Lucas Chess's acqua engine is the weaker I could find (and the engine file can be found on the software folder).

Alternatively, The Soviet Chess Primer by Ilya Maizelis. This was Karpov's and Kasparov's first chess book and ton of strong players still recommend it. This deals with from the absolute ground up and I think should get you to at least a thousand. If you are going to use this, however, make sure you supplement it with either puzzle books or puzzle programs. I really like Lucas Chess for this purpose.

Are any of the Maia bots good for this? With Lucas Chess (free, download) you can play the Maia bots from any position, I think.

Try Lucas Chess or look through this list for more.

Appears to be GPLv3 https://github.com/lukasmonk/lucaschessR

Lucas Chess lets you save diagrams as images. Scid Vs PC lets you export HTML, LaTeX, etc. I haven't tried it but if it works, this is probably the most customizable option.

FuzzyExit linked this one, which seems to have some really cool features you might take inspiration from: https://lucaschess.pythonanywhere.com/

Lucas Chess and Deep Shredder would be my recommendations. You can load and play all sorts of engines in Lucas Chess, so once you find the perfect engine out there for your Dad you can just set that as the default everytime.

The code shows the engines are there still: https://github.com/lukasmonk/lucaschessR/tree/master/bin/OS/win32/Engines

A little sidenote and in addition to all the great advices written here - I found a little command-line blind-chess program called Piñata which allows one to play against engines using algebraic notation input and output. You will need to download an engine file of your choice and put it on the same folder.