Latest Fire OS 7 user agents:

User Agent Browser Device
Mozilla/5.0 (Linux; Android 9; KFTRWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 [FB_IAB/FB4A;FBAV/464.0.0.60.90;] Facebook 464 Fire HD 10 (2021)
Mozilla/5.0 (Linux; Android 9; KFTRPWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 Instagram 278.0.0.22.117 Android (28/9; 240dpi; 1200x1848; Amazon; KFTRPWI; trona; mt8183; en_US; 471827207) Instagram 278 Fire HD 10 Plus (2021)
Mozilla/5.0 (Linux; Android 9; KFMUWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 Instagram 395.0.0.56.165 Android (28/9; 160dpi; 600x976; Amazon; KFMUWI; mustang; mt8163; fr_CA; 783189161; IABMV/1) Instagram 395 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 9; KFONWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/138.12.1 like Chrome/138.0.7204.244 Safari/537.36 Mobile Silk 138 Fire HD 8 (2020)
Mozilla/5.0 (Linux; Android 9; KFTRWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 [FB_IAB/FB4A;FBAV/540.0.0.49.148;IABMV/1;] Facebook 540 Fire HD 10 (2021)
Mozilla/5.0 (Linux; Android 9; KFTRPWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 [FB_IAB/FB4A;FBAV/493.0.0.72.158;] Facebook 493 Fire HD 10 Plus (2021)
Mozilla/5.0 (Linux; Android 9; KFKAWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 [FB_IAB/FB4A;FBAV/547.0.0.41.68;IABMV/1;] Facebook 547 Fire HD 8 (2018)
Mozilla/5.0 (Linux; Android 9; KFTRWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 [FB_IAB/FB4A;FBAV/486.0.0.66.70;] Facebook 486 Fire HD 10 (2021)
Mozilla/5.0 (Linux; Android 9; KFTRPWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.224 Safari/537.36 Instagram 419.0.0.49.71 Android (28/9; 240dpi; 1200x1920; Amazon; KFTRPWI; trona; mt8183; en_US; 896334196; IABMV/1) Instagram 419 Fire HD 10 Plus (2021)
Mozilla/5.0 (Linux; Android 9; KFTRPWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.224 Safari/537.36 [FB_IAB/FB4A;FBAV/551.1.0.58.63;IABMV/1;] Facebook 551 Fire HD 10 Plus (2021)
Mozilla/5.0 (Linux; Android 9; KFKAWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 [FB_IAB/FB4A;FBAV/545.0.0.43.63;IABMV/1;] Facebook 545 Fire HD 8 (2018)
Mozilla/5.0 (Linux; Android 9; KFTRWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 [FB_IAB/FB4A;FBAV/544.0.0.42.272;IABMV/1;] Facebook 544 Fire HD 10 (2021)
Mozilla/5.0 (Linux; Android 9; KFMAWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 [FB_IAB/FB4A;FBAV/490.0.0.63.82;] Facebook 490 Fire HD 10 (2019)
Mozilla/5.0 (Linux; Android 9; KFTRWI Build/PS7331.4463N) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 [FB_IAB/FB4A;FBAV/551.1.0.58.63;IABMV/1;] Facebook 551 Fire HD 10 (2021)
Mozilla/5.0 (Linux; Android 9; KFMAWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 [FB_IAB/FB4A;FBAV/533.0.0.49.79;IABMV/1;] Facebook 533 Fire HD 10 (2019)
Mozilla/5.0 (Linux; Android 9; KFMAWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 [FB_IAB/FB4A;FBAV/546.0.0.42.66;IABMV/1;] Facebook 546 Fire HD 10 (2019)
Mozilla/5.0 (Linux; Android 9; AFTSSS Build/PS7712.5370N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Mobile Safari/537.36 Chrome Webview 138 Fire TV Stick (Gen 3)
Mozilla/5.0 (Linux; Android 9; AFTSSS Build/PS7711.5273N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Mobile Safari/537.36 Chrome Webview 138 Fire TV Stick (Gen 3)
Hulu/1.177.1 (Fire OS 7.7.1.1 (PS7711/5272); ; AFTHA004; Build/Neutron - 1.4.559) Hulu 1 Fire TV 4K (2022)
Mozilla/5.0 (Linux; Android 9; KFTRWI Build/PS7331.4463N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Safari/537.36 [FB_IAB/FB4A;FBAV/412.0.0.22.115;] Facebook 412 Fire HD 10 (2021)