My PhD Supervisor is founding a startup based on my thesis work and wants me to be first hire. Unsure if want to join

I’m a current PhD student and PhD supervisor is in the process of making a startup company largely based on the devices that I’ve developed during my PhD thesis. My supervisor is trying hard to convince me, but not pressuring me, to join the company as its first hire. If I accept I will almost immediately begin writing my thesis to graduate early as I begin to work at the company.

I will make a modest salary to begin with (A 10K-15K increase in my PhD salary, but probably 30K-40K less than I could expect to make if I was hired at a larger company) and get roughly 2% equity. He is looking for me to commit for a year to 2 years to begin with, at which point he thinks we can bring the company to a roughly 20M valuation if successful.

I enjoy the work I do and have a relatively okay relationship with my advisor, but am beginning to get some fatigue and am interested in getting the opportunity to work on something new. At the startup I would essentially be doing the same work I’m doing now and continue working in the same labs and using the same equipment. This makes it difficult for me to get 100% excited about the opportunity because there is not really an immediately tangible change or benefit that feels like career progression other than the small increase in pay, and potential future payout if the company is successful.

I don’t want to accept the offer and within my first few weeks feel like I’m already burnt out on the project. But I also don’t want to pass on the offer, find my new job not as exciting (or not be able to find a job at all) and wish I would have accepted the offer. Does anybody have any advice? Thanks.