Ask HN: Why is there no open-source solution to migrate WA Android to iPhone?

I have recently bought an iPhone and to my surprise I found that there is no free solution available on the internet to migrate your WhatsApp history from Android to iPhone. I noticed there are few paid solutions like dr.fone which claim to do that for a fee. Then I guess technically it is possible, right?

So did anyone not try it write an open-source solution? I plan to explore it and willing to write up script/solution/playbook if it is possible to be done in max 2 days of effort. Any ideas/suggestions?