Email is the reliable channel. I read everything that was clearly written by a person, and I answer most of it.
We save a round trip if the first message says what you are building or fixing, what already exists on your side, and what the constraint is — a date, a budget, a regulatory requirement, or a team that has to run it after handover. Without those three sentences I will only ask.
If something comes of it, the next step is usually a half-hour call with no slides, in which I mostly ask questions.
I am also glad to get a question with nothing attached to it: whether the architecture you already have is sensible, or whether BigQuery is the right answer for your case. Sometimes it is not.
LinkedIn works too, the messages just sit there longer than I would like.