update webview, impossible through playstore, any idea?

[AltCtrlDroid]

hallo freaktab community!
I'have got a three sunnzo s9 max, I have bought them for work as kiosk devices, they are good for render videos and html5 pages and natively support touchscreens.
Unfortunely is not possible to update the system webview (is at version 74....) thru playstore.
My tests:
Follow stupid guides to install webview from playstore (clear cache, disable developer options etc) = don't works
push bromite webview in system folder = bootloop
test slimbox for my device=dont tested if supports touch
flash a new firmware taken from official sunnzo page, the webview now is more recent but i have lost root, ethernet and bluetooth functions (this solution is good, but how to restore these features?)


any ideas/suggestion?
I want to try to push another webview version from adb or twrp, but before waste time I prefer to ask !

Thanks!

[mAtvXk]

Sideload it from APKmirror.

[mAtvXk]

Sideload it from APKmirror.

[AltCtrlDroid]

used this procedure, it works and the webview seems updated (webview version number in developer options changed) BUT fully kiosk browser (the app i need to use for my work) do not find any webview installed.
I have rollback to previuos version, i think that is not so important to update webview for an offline kiosk...
Thank you anyway