For those of you with Galaxy S6 SM-G920F or SM-G920I, we have been constantly adding stock firmwares for it on our Galaxy S6 stock firmware page.
We are still adding more stock firmwares but there should be plenty enough to work with right now. Also, you can cross-country flash another country firmware so long as you have the same model number. For example, if you have SM-G920F German model, you can also flash the France SM-G920F firmware. Now, so long as the country firmware you are using now doesn’t include country-specific apps (such as carrier bloatware), you should be fine. If you absolutely need a Galaxy S6 stock firmware for your country, shoot me an e-mail at zedomax [at] gmail dot com and we will get your firmware uploaded first.
For now, there’s also T-Mobile and Sprint stock firmwares for the SM-G920T and the SM-G920P. We are still working on getting hands on AT&T and Verizon firmwares but in the past, AT&T and Verizon firmwares are harder to get due to its locked bootloaders and carrier cock blocking. But we will definitely get those eventually.