First, speaking from experience of someone who worked in a (failed) project that wanted to build a "Enterprise version of ChromeOS", based on Firefox and Linux: I love this naive confidence to predict how much it would cost to bring a whole new lot of features to a product (Firefox/Gecko) that is known for being extremely difficult to refactor.
Second, You really don't get it, do you? They will not spend money on anything that might actually threaten Google's dominance. They get 30M to play with AI is because they don't get to spend anything on making Firefox a strong alternative for Chrome. If they did, Google will take all their money away and then it's game over for them.