The tyres seem to be a tubeless system TCS.
I'm not that interested in buying 2 wheelsets unless there are any deals
Are there any gravel bikes on reduced sale with decent specs?
If you are going to run tubeless, swapping tyres sealant etc to ride on the road is going to get tiresome, even clincher and tubes would pish me off. Would probably just ride the road with knobbly tyres in the end. Schwalbe S One and G-One are pretty road usable, I have done loads of road miles on the S-Ones without much penalty speed wise.
How off road is the off road you are going to be doing? That's the main question really. Trails, towpaths and loose chip seal etc most bikes will handle all you really need is a bit of tyre clearance. If you are doing full on muddy cyclocross MTB type off road then you will be better off with CX type bike to run knobbly tyres.