Latest Facebook Messenger 128 user agents:

User Agent Platform Device
Mozilla/5.0 (Linux; Android 7.0; STARTRAIL 9 Build/NRD90M; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/55.0.2883.91 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/128.0.0.21.88;] Android 7 StarTrail 9
Mozilla/5.0 (Linux; Android 7.0; SM-G610F Build/NRD90M; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/60.0.3112.116 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/128.0.0.21.88;] Android 7 Galaxy J7 Prime
Mozilla/5.0 (Linux; Android 6.0.1; vivo Y55 Build/MMB29M; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/59.0.3071.125 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/128.0.0.21.88;] Android 6 Y55
Mozilla/5.0 (Linux; Android 5.1; HUAWEI CUN-L21 Build/HUAWEICUN-L21; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/59.0.3071.125 Mobile Safari/537.36 [FB_IAB/MESSENGER;FBAV/128.0.0.21.88;] Android 5 Y5II