"approached by a funded startup" implies to me that your are being asked to be employee #N. You are unlikely to have any significant equity percentage, and tha

"approached by a funded startup" implies to me that your are being asked to be employee #N. You are unlikely to have any significant equity percentage, and that equity will almost definitely be in a category that only receives any money after the funders and founders are well-compensated. In short, consider it a job - any payout from the acquisition will be minimal. Evaluate the job based on the work you'll be doing and the immediate compensation you will receive, and even more than when working for a stable company, be prepared to move on whether by your choice or events beyond your control.