There's quite neat lexer and parser generators for Python that can ease the barrier to entry. For example, I've used PLY now and then for very small things.

On the non-generated side, lexer creation is largely mechanical - even if you write it by hand. For example, if you vaguely understand the idea of expressing a disjunctive regular expression as a state machine (its DFA), you can plug that into skeleton algorithms and get a lexer out (for example, the algorithm shown in Reps' "“Maximal-Munch” Tokenization in Linear Time " paper). For parsing, taking a day or two to really understand Pratt parsing is incredibly valuable. Then, recursive descent is fairly intuitive to learn and implement, and Pratt parsing is a nice way to structure your parser for the more expressive parts of your language's grammar.

Nowadays, Python has a match (pattern matching) construct - even if its semantics are somewhat questionable (and potentially error-prone). Overall, though, I don't find Python too unenjoyable for compiler-related programming: dataclasses (and match) have really improved the situation.