To be fair, this particular design seems to be one of those common Chinese ones used by any company who wants to make a phone. It's really easy to assemble, hard to disassemble. It's been used in countless Xiaomi phones, lesser known Chinese brands, even Samsung seems to have borrowed from it.

It's the same basic design as the OnePlus 6/6t, boards and battery glue sandwiched between two pieces of glass (the front one being the screen itself). If they skip on the material and fit quality (like Xiaomi does), it can be done for really cheap in any semi-decent factory.

If my experience with anything MediaTek still holds, they better use a good heatsink, because their chips get hot, and they die from it, too.