At first glance I felt that 100k wasn't really going to move the needle in creating a new browser engine but in fact (after reading the link below) it's not insignificant. There are a lot of contributers to this project, and funding the project lead is a big step in the right direction.
Realistically another browser engine really isn't needed. 2 is enough. Given the scale of the work involved it'll take a lot more than money to make this mainstream.
Bur that doesn't mean it's not important. These sorts of projects have value beyond main-stream use cases. While those uses are small, they can end up being significant.
[1] https://awesomekling.github.io/Ladybird-a-new-cross-platform...