These tiny yellow white spots close to lips or your cheek mucosa inside could mostly be Fordyce spots, a presentation of oily gland (sebaceous gland) at unusual sites. They don’t cause any disease as such, nothing to worry. They may be a cosmetic concern for few, in that case few surface treatments are available. But, since you mentioned it’s inside your mouth, shouldn’t be a concern. Keep a check it isn’t changing it’s presentation drastically (shape/texture/colour/discharge if any)