It's really in the best interest of everyone using it to chip in and keep the project relevant. Unfortunately the amount of donations is going to be contingent on the size of its user base which will need to grow to ensure its longevity.
Sure, but one is much more likely to have some ARM(64) SBC / smartphone / tablet / IoT device laying around than a SPARC box. Those are much more likely to have Linux than NetBSD drivers. Support for ancient architectures doesn't matter nearly as much as that.