How many ohms can the headphone jack in the 2020 M1 MBP power?

This article does not describe your exact model MacBook Pro. But it does describe Apple's thinking about what a headphone output should be in terms of 'Regular' and 'High-impedence':

Use high-impedance headphones with MacBook Air, MacBook Pro, or Mac Studio - Apple Support

Based on that information, I think the answer to your query as written is "150 Ohms or less".