From bigclivedotcom.

I’m sure there are great vacuum seal bags that work effortlessly first time, but then there are the type that may require a little persuasion to start working.

The secret is in understanding how the cost-optimised one way valve works, and how it may require a bit of priming to get it started.

It’s also useful to squeeze as much air out of the bag as possible before zipping the seal up and pulling the vacuum as it saves a lot of time.

It appears that there are some 3D printing files available for making support and airflow disks to use under the seal in these bags to make them work better.

I ended up getting a rechargeable pump, and it still takes a while to suck all the air out.

These bag and pump kits are very common on AliExpress (not a sponsor). Here’s a typical listing.
https://www.aliexpress.com/item/1005008585669872.html