Looks good so far. I maintain a SaaS that hosts this for you, the amount of lessons I've learned to scale this up were very fun and others frustrating.
I also use whatsmeow but had to add some layers for tenant isolation and resource manangement. I was able to come up with an image as little as 30mb and full control over the resources - uses as little as 60mb of RAM.
Nice! Did you run this as a hosted service for companies that wanted full access to their WhatsApp? I just wonder how you made it work with trust? Was it fully closed sourced, on your servers?
I could imagine that users would want to see how and where the data is stored.