I often have conditional filtering in my queries which causes beam to produce where clauses that look like WHERE ((true) AND (true)) AND (true).... It seems it would be easy to clean this up when building the queries by just realizing that a known (val_ True) combined with &&. can simplify to one side or the other. I'm not sure if this is "in-scope" with this project, but if it were easy, it would make the resulting queries cleaner.
I could see an argument against this if one wanted to have a very clear 1-to-1 correspondence between the beam DSL and generated SQL.