Is this equity enough compared to typical values for first technical hires? I will not promote

Been offered to join a new startup that has raised about 300M so far. Id be one of their first technical hires to run their whole R&D department (which doesnt yet exist and I will have to build). They offered me a nice base salary for the region and 0.25% equity post raise with a supposed valuation of 1B. Initially I will have to be doing a lot more development than research to get the first plant off the ground, but hopefully after an initial push to build the structures of the company I can focus more on the cool part. I am wondering if this amount of equity is common or should I be asking for more? I will ask for more eother way, but if they dont give it to me I wanna know if its a good deal for the amount of effort.