A quick reminder, if you wanna connect your Android device to an Arch linux distro running KDE, you could use KDE Connect. Supposed you have already kdeconnect runnig on your machine and the app KDE Connect on your phone, all you need to do access any sort of life on the latter is to open the app and enable the Filesystem expose plugin and choose the folders you wanna give access to.

However, this might still give you some error. In that case, just do sudo pacman -Sy sshfs. Once that package is installed, Dolphin should allow you to broswe through the allowed folders of your phone.

Hit me, if you have any problem.