What is the percentage of the population whose actual mother tongue is Mandarin?
The mother tongue would be the language that someone learned at home from their family members
There seems to only be stats for &quot;speaker&quot; amounts and not strictly native speakers.

Firstly, 'mother tongue' and 'native' are not the same.
My mother tongue is officially Mandarin Chinese, and I used to speak it a lot at home, but my native language is English, which is my strongest language. Well, depending on perspective, people like me might be considered as having two native languages.
If that is so, then everyone whose mother tongue is Mandarin Chinese must be a native speaker, which makes it a subset.
As people whose mother tongue is Mandarin Chinese (836 million) is a subset of people whose native language is Mandarin Chinese, (960 million) I think that it is safe to assume that the map provided by @Stan is an accurate depiction of the population whose actual mother tongue is Mandarin Chinese.
Given those numbers, the percentage would be 87%. However, we do know that while some people's official mother tongue is Mandarin Chinese, they may not pursue it, which makes this statistic inaccurate. So there might be around a 10% margin of error if we were to assume that only Chinese people in China pursue their mother tongue as native language.