I think SFTP would work plenty. On linux you can use rclone to mount it, and Android has many file managers that support it (personal favorite is Total Commander with the SFTP plugin)
You could also certainly host a full Nextcloud instance, but it might be a bit overkill
I think SFTP would work plenty. On linux you can use rclone to mount it, and Android has many file managers that support it (personal favorite is Total Commander with the SFTP plugin)
You could also certainly host a full Nextcloud instance, but it might be a bit overkill