Are third-party Roborock parts good enough for most people?

Regarding the Roborock: Yes, for the most part. Filters and brushes from third-party brands work well enough that you’d have to be very picky to notice a difference. Third-party filters are about 70% as effective at 20% the price, and brushes are often the same plastic from the same factory. Just avoid cheap knockoff mop pads or ill-fitting main brushes, and stick to well-reviewed sellers.