Additional typing hints

[Leengit]

With the goal of making it easier to detect when errors are introduced with future code changes:

• Adding types for additional variables and parameters.
• Making mypy and tox / ruff complain less about the code.

Also, minor performance improvements like:

• Invoking all(my_generator) rather than via list: all(list(my_generator)) or all([x for x in my_geneator]).
• Invoking dict(zip(keys, values)) rather than {key: value for key, value in zip(keys, values)}