It’s reasonable to ask “what percentage does this represent on a fully-diluted basis?”

It is entirely unreasonable to ask for a percentage of the company which can never be diluted by a future fund-raising round. Doing so just telegraphs that you don’t know how venture funding/corporate finance works.

I imagine that that would be really hard to achieve (or manage for the company) in practice, although I'd love to see a world in which employees could essentially get pro rata rights to purchase more shares built into their employment. That'd allow them to participate more fully in the upside of companies taking off like rocket ships.