Earlier quoted context omitted.
Rebble sounds pretty much like a non profit to me > The Rebble Foundation is a non-profit organization that keeps the Pebble community alive. rebble.io https://rebble.foundation/
They aren't a 501c3. When I wrote my original comment I did a search for Rebble among all 501c3 ores and they are not there. I looked closer after your comment. They appear to be a "Michigan Domestic Non-Profit Corporation". Why aren't they a 501c3? I have no idea. It makes me trust them less to be honest, that they are some sort of nonprofit but not a 501c3.
I think you have a misunderstanding of how that works. In many cases, you need both the state and federal non-profit designation (i.e. a Michigan domestic non-profit corporation would not pay state income taxes on charitable income + that same corporation would need the 501c3 designation from the IRS to have the same benefit at the federal level).
Do you have positive confirmation that they are not filing as a 501c3?