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/553.0.0.56.58;IABMV/1;] Facebook 553 Fire HD 10 (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/535.0.0.49.72;IABMV/1;] Facebook 535 Fire HD 8 (2018)
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/554.0.0.57.70;IABMV/1;] Facebook 554 Fire HD 10 (2019)
Mozilla/5.0 (Linux; Android 9; KFONWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/138.13.4 like Chrome/138.0.7204.244 Safari/537.36 Mobile Silk 138 Fire HD 8 (2020)
Mozilla/5.0 (Linux; Android 9; KFKAWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/138.13.4 like Chrome/138.0.7204.244 Safari/537.36 Mobile Silk 138 Fire HD 8 (2018)
Mozilla/5.0 (Linux; Android 9; AFTSS) AppleWebKit/537.36 (KHTML, like Gecko) Silk/138.13.4 like Chrome/138.0.7204.244 Safari/537.36 Mobile Silk 138 Fire TV Stick Lite (Gen 1)
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[FBAN/EMA;FBLC/en_US;FBAV/500.0.0.8.103;FBCX/modulariab;] Facebook Lite 500 Fire HD 10 (2021)
Mozilla/5.0 (Linux; Android 9; KFONWI 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/469.2.0.51.80;] Facebook 469 Fire HD 8 (2020)
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/483.0.0.51.72;] Facebook 483 Fire HD 10 Plus (2021)
Mozilla/5.0 (Linux; Android 9; KFMAWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/138.13.4 like Chrome/138.0.7204.244 Safari/537.36 Mobile Silk 138 Fire HD 10 (2019)
Mozilla/5.0 (Linux; Android 9; AFTKA) AppleWebKit/537.36 (KHTML, like Gecko) Silk/138.13.4 like Chrome/138.0.7204.244 Safari/537.36 Mobile Silk 138 Fire TV Stick 4K Max
Mozilla/5.0 (Linux; Android 9; KFTRWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/138.12.1 like Chrome/138.0.7204.244 Safari/537.36 Mobile Silk 138 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/553.0.0.56.58;IABMV/1;] Facebook 553 Fire HD 10 (2019)
Mozilla/5.0 (Linux; Android 9; AFTCA002 Build/PMAIN1.304N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Mobile Safari/537.36 Chrome Webview 138 Unknown
Mozilla/5.0 (Linux; Android 9; AFTMD002 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 3-Series (2023)
Mozilla/5.0 (Linux; Android 9; KFONWI 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/553.0.0.56.58;IABMV/1;] Facebook 553 Fire HD 8 (2020)
Mozilla/5.0 (Linux; Android 9; AFTR Build/PS7712.5374N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Mobile Safari/537.36 Chrome Webview 138 Fire TV Cube (Gen 2)
Mozilla/5.0 (Linux; Android 9; KFTRWI) AppleWebKit/537.36 (KHTML, like Gecko) Silk/138.13.4 like Chrome/138.0.7204.244 Safari/537.36 Mobile Silk 138 Fire HD 10 (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 Chrome Webview 138 Fire 7" (2019)
Mozilla/5.0 (Linux; Android 9; AFTGAZL Build/PS7712.5371N; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/138.0.7204.244 Mobile Safari/537.36 Chrome Webview 138 Fire TV Cube (Gen 3)