How to open link with sakura?

That's right. It uses the BROWSER environment variable. If it is not already configured it should be added to your bash, zsh or whatever shell configuration files your system uses.

I forgot to mention that I already have $BROWSER=w3m set in my .bashrc, but it doesn't help here

$ echo $BROWSER
w3m

I see, right now it doesn't work with text browsers, this option was added with graphical browsers in mind (actually it kind of works if you open the link from a sakura terminal launched from another sakura teminal, but that isn't an intended behavior)

It doesn't work with GUI browsers either, I tried after changing BROWSER to lariza and it still failed. However if I open sakura from sakura it works with both text and GUI browsers.

Do you have xdg-open installed in your system? If there isn't a BROWSER env variable, sakura uses xdg-open to launch you preferred browser. This is the best way in my opinion, instead of using the BROWSER variable.

Yes after removing BROWSER env variable from bashrc and setting lariza.desktop as default-browser in xdg-settings, open-link with sakura works. Thanks