We yet not have the POST APIs available. Our major release is scheduled this week, then we will start working on this. If you need it soon, you can request for customisation.
That seems great. Let us know what all the help you need from our side. Also, would it be possible to connect on Skype to discuss further more on this?
You can connect us here: https://join.skype.com/invite/PcxhAmHq0o7C
The last php version on which bagisto works is 7.2