Google's Sundar Pichai took home $226 million for managing 182,000 employees and making $305.6 billion in revenue, so $1,238 per employee and 0.07% of revenue.
Mozilla's Mitchell Baker took home $6.9 million for managing 750 employees and making $593 million in revenue, so $9,200 per employee and 1.16% of revenue.
The Metropolitan Museum of Art's CEO earns $1.28M with 2000 employees and revenue of $328 million, which is $640 per employee and 0.4% of revenue. Although I can't say for sure whether that figure is full-time-equivalent employees or if they have a large number of part time staff.
So you might consider the Mozilla CEO's salary very low or very high, depending on what you mean by "comparable"
In terms of value for money - a generous salary might be justified if Mozilla is a thriving organisation that's going from strength to strength thanks to the wisdom of its leadership. But is it?