convert T239c and T355c to international or add google

a friend came back from china with 2 tablets

• SM-T239C Galaxy Tab 4 Lite 7.0


• SM-T355C Galaxy Tab A 8.0

they work great with only 1 issue... no google apps, and as china only models it's an issue to add it to them

can anyone help to convert them to normal models or just add google apps?

convert marshmalo to KitKat

how to convert back my canvas a1 marshmalo to KitKat
becoz I don't like a marshmalo