text to time

I see you mentioned using Direct query, I would suggest using Native query

1. Creating your model with the property "Direct Query Mode: Off".

-Then, If you create your own query, using Sql.Database()

let
    database name
    Source = Sql.Database("MyConnection", "DATABASE", [Query="
        SELECT
            departure_time,
            -- Convert departure_time (HH:MM) to total minutes
            CAST(split_part(departure_time, ':', 1) AS INTEGER) * 60 + CAST(split_part(departure_time, ':', 2) AS INTEGER) AS total_minutes
        FROM
            transport_schedule
    "]),
    // if needed
    CleanedData = Table.SelectRows(Source, each [total_minutes] > 0)  // Example of filtering
in
    CleanedData

 -Once transformation is done you may switch to "Direct Query Mode: On"

That might work!