Latest Fire OS 6 user agents:

User Agent Browser Device
Mozilla/5.0 (Linux; Android 7.4.3; KFTHWI Build/KTU84M) AppleWebKit/537.36 (KHTML, like Gecko) Silk/97.1.79 like Chrome/97.0.2526.80 Safari/537.36 Mobile Silk 97 Kindle Fire HDX 7" WiFi
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/85.3.5 like Chrome/85.0.4183.126 Safari/537.36 Mobile Silk 85 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/85.2.3 like Chrome/85.0.4183.101 Safari/537.36 Mobile Silk 85 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/84.3.5 like Chrome/84.0.4147.125 Safari/537.36 Mobile Silk 84 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/84.1.153 like Chrome/84.0.4147.111 Safari/537.36 Mobile Silk 84 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/83.4.3 like Chrome/83.0.4103.106 Safari/537.36 Mobile Silk 83 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/83.3.11 like Chrome/83.0.4103.106 Safari/537.36 Mobile Silk 83 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/83.2.20 like Chrome/83.0.4103.106 Safari/537.36 Mobile Silk 83 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/83.1.130 like Chrome/83.0.4103.101 Safari/537.36 Mobile Silk 83 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/81.2.16 like Chrome/81.0.4044.138 Safari/537.36 Mobile Silk 81 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/81.1.233 like Chrome/81.0.4044.117 Safari/537.36 Mobile Silk 81 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/80.5.3 like Chrome/80.0.3987.162 Safari/537.36 Mobile Silk 80 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/80.4.14 like Chrome/80.0.3987.119 Safari/537.36 Mobile Silk 80 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/80.3.2 like Chrome/80.0.3987.132 Safari/537.36 Mobile Silk 80 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/80.2.5 like Chrome/80.0.3987.119 Safari/537.36 Mobile Silk 80 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/80.1.144 like Chrome/80.0.3987.119 Safari/537.36 Mobile Silk 80 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/79.4.9 like Chrome/79.0.3945.136 Safari/537.36 Mobile Silk 79 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/79.3.13 like Chrome/79.0.3945.116 Safari/537.36 Mobile Silk 79 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/79.1.135 like Chrome/79.0.3945.93 Safari/537.36 Mobile Silk 79 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 7.1.2; KFMUWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/78.5.26 like Chrome/78.0.3904.108 Safari/537.36 Mobile Silk 78 Fire 7" (2019)