nice project ! and attempt to modernize the spreadsheet tech stack. be warned though, that the feature-set of the modern spreadsheet is gigantic, with tentacles in hundreds of nooks and corners. Any attempt to play catch-up is a losing proposition. Hence you could position it so as not to directly compete with excel - in areas that are new or emerging.

trivia: js based https://ethercalc.net/ is in turn is derived from https://github.com/DanBricklin/socialcalc written by the spreadsheet inventor dan bricklin