Where it goes
Time. I have a full time job. Deki gets evenings and weekends. Donations turn stolen hours into whole days, which is when the useful stuff happens: docs, new boards, releases that actually ship.
Boards. Every device Deki runs on is a device I bought and keep on my desk. The pile keeps growing. The next one starts as an order.
What you get
Everyone gets the same Deki: all of it, free, Apache 2.0. Keeping it that way is what you are paying for.
You will see where the money went. Releases, new boards working, docs that turned up this month. It all lands on the blog and inDiscord.
Want something built for you specifically? That is a normal thing to ask, and a different one. Catch me on Discord.