You can use a boost converter to boost the 5V of an USB port to the 19V your notebook needs.

Assuming 5A output from a powerbank (which is probably about the max you will get without USB PD), you could theoretically get 0.55A at 19V. With the unavoidable inefficiencies, you will get less.

So, maybe enough to very slowly charge your notebook while it’s off. But when it’s turned on, the battery charge will still drop.