I answered first with generic comments, but when looking at your specific board, it seems to be a rather rare SDcard based one, and it does support ext4. So my comment for that was wrong.
But I am not sure if it supports sysupgrade at all.
No trace of sysupgrade image .bin.
Possibly (likely) it is not supported for your device.
Or alternatively, that sdcard.img.gz might be accepted by the sysupgrade routine. It has the append-metadata step, which suggest that OpenWrt sysupgrade metadata is added and sysupgrade might accept it.
Right i activated using menuconfig generation of image file through sdcard and the associated file sdcard.img.gz was able to load on sysupgrade tool. But after i loose my sdcard contents because only updated files were upgraded ? , i guess it's because the architecture was not same. Anyway i will try a fresh install using sdcard file then retry sysupgrade after some modifications. Will let you know ...
I can confirm that using the generated image sdcard (openwrt-mvebu-cortexa53-globalscale-espressobin-ext4-sdcard.img.gz) on Luci and sysupgrade feature I can upgrade the system it works but it delete everything, so it’s not useful that way ? I would like to upgrade but without loosing what I installed before ... how to ?
I can confirm that using the generated image sdcard (openwrt-mvebu-cortexa53-globalscale-espressobin-ext4-sdcard.img.gz) on Luci and sysupgrade feature I can upgrade the system. In fact it restore with keep of configuration but package installed in remote are lost.
Your support was great and in particular @hnyman Thank you !