may flash with TWRP
you recommend to use ubuntu-device-flash
but i use to flash with TWRP with great backup function
is it compatible still have TWRP after flash ?
and if not how to put ubuntu touch with TWRP ?
yeaaaah google is your friend (sometime)
somethings i will read before...
How to Flash Ubuntu Touch on OPO using TWRP
so this tutorial use image from twrp backup ... :o(