No, probably not. This 20 mm Quick Release strap isn’t suitable for an MK3i with a 20 mm QuickFit strap, as QuickFit and Quick Release aren’t compatible with each other.
The 20 mm leather strap listed in your details is designed for Quick Release and, according to the available information, is compatible with the Fitbit Luxe and Garmin Forerunner 245 Music, but not with an MK3i.
No, this 20 mm wide Milanaise strap does not fit the Garmin Venu 3S. The Venu 3S uses 18 mm wide straps, while this strap is designed for models such as the Venu and Approach S40.
The "Quick Change (20 mm, Nylon)" strap does not fit the Garmin vivomove Trend, as it is intended for models such as Forerunner 645, Venu, Vivoactive 3 and various Vivomove models (HR, Style, 3) with a 20 mm strap width, but the vivomove Trend is not included in the compatibility list. The vivomove Trend apparently uses a different strap size or system [product data].
The quick-change wristband with a width of 20 mm is specially designed for the Garmin Venu SQ and Venu SQ Music. It is not directly compatible with the Garmin Venu 2 Plus, as this may have a slightly different bridge width, as mentioned in some reports. If you are looking for a black replacement strap for the Garmin Venu 2 Plus, you should look for specific straps for this model.