It states that employees can't receive more than $100,000 worth of exercisable ISOs in a given calendar year. Any amount beyond that will be taxed as if the ISOs are NSOs.
The short answer is yes. However, you have to ensure that your offering is compliant with all the relevant regulations in both your and your contractor's country. In some regions, for instance, your contractor may be eligible to receive non-qualifying stock options, but your contractors in other countries may not.
However, there are some downsides: Options being worthless if the stock value of the company doesn't grow. The possible dilution of other shareholders' equity when option-holders exercise their stock options. Complex tax implications for ISOs, especially the concept of AMT.
Between these two main types of stock options, NSO and ISO, you want to know which one to use for your startup's requirements. Some important distinctions between NSO and ISO: NSO may be granted to employees and non-employees (advisors, consultants, board members), whereas ISOs can only be granted to employees.
Private limited companies especially companies in early stages of business or startups typically like to grant employee stock options (ESOPs) to part time employees, advisors, mentors, consultants and co-founders.
The short answer is yes. However, you have to ensure that your offering is compliant with all the relevant regulations in both your and your contractor's country.