Can’t be said (and read) enough. The left (or any other political faction) does not have traction without the legislature. Federal, yes, but also state. (See: Texas’ draconian anti-abortion laws, North Carolina’s disastrous and unnecessary anti-trans law, etc.)
Writing one’s Republican representatives is only slightly more productive than screaming into the void but so is voting silently for your preferred candidate. Keep doing both of these things but don’t limit yourself to them.
Which brings me to my concluding question: what else should we be doing?