Can Importance.none on Android guarantee that a notification is completely hidden from the shade across all OEM skins?

Goal: Configure a Flutter local notification that produces no sound, vibration, or heads‑up banner while still allowing the user to see it in the notification shade if they choose.

Constraint: On Android, Importance.low suppresses auditory and visual interruptions but some OEM skins still show low‑importance notifications; Importance.none is intended to hide the notification entirely, yet its consistency across manufacturers is unclear.

Question: Does setting Importance.none on Android reliably prevent the notification from appearing in the shade on all major OEM skins (e.g., Samsung, Xiaomi, Huawei, OnePlus)? If not, what alternative configuration achieves a truly silent notification that remains accessible only through the shade?