Hello @krisbee22
The Nest WiFi Router appears to support 2x2 streams in the 2.4GHz band. Each stream can negotiate, at most, 150Mbps. So, any client devices that can also support 2x2 streams will be able to communicate with the Nest WiFi Router at 300Mbps. However, some clients may only have 1x1 stream radios. When they're using the 2.4GHz channel, they will only be talking at 150Mbps (at most).
In addition, the further away the clients are, the slower they will have to communicate. Luckily, 2.4GHz carries further and penetrates obstructions better than 5GHz. But, it still falls off with distance and obstructions.
One way a system like Google/Nest WiFi can help with 2.4GHz capacity is by using additional Nest WiFi Router or Point units (or Google WiFi units), since they can select a different 2.4GHz channel than the primary router. They talk to the primary using 5GHz, and carry any client traffic back and forth on that band. This has two impacts. First, it roughly doubles the total capacity in the 2.4GHz band. Second, since the secondary is 30-40 feet away from the primary, it expands the coverage area, increasing the chances a 2.4GHz client may be able to negotiate a higher link speed.
I know this is a lot of information. But, unfortunately, this is a complex topic, so it's hard to boil it down to a simple "X number of Mbps" answer. Your current router is subject to most of these same considerations as well.
