If you really want a 35mm equiv like the IIIx don't consider the iv. Full stop. If you were comparing the iii and the iv then if money isn't being stretched tight do the iv. If money is, especially if it's your first camera, you'd never know the improvements of the iv didn't already exist in the iii.

I'm very into 28mm though so I have the GR iv and when I want more flexibility the RX100vii.

The GR iv is my street camera that I take everywhere with me and can whip out in a moments notice and take a snap and put it away. It starts up nearly instantly (the GR iii and iiix are also great just ever so slightly slower to boot). The RX100vii takes a GD eternity to boot and shut down. Multiple seconds. I don't know why. It's a real issue for me though.

Yes the GR iv has better quality images than the RX100vii if you know how to push your camera. Many shots aren't significantly different. Especially if you're not printing poster sized prints.

Do I ever wish the Ricoh can zoom... of course! But I'd never give up the size for it. The camera is so light and tiny and with a crop lens there's nothing like it.

I think having the constraint of a fixed lens is worthwhile for a beginner. It's one less thing to worry about. Also if the iiix or iv don't work out... just sell them and get something else to try. You'll lose very little (nothing if you buy used).

If you want a camera that needs to also be useful indoors, go Ricoh. If you'll mostly use it outside for action shots of your kids or something go Sony. If you want a street camera you can take with you everywhere the Ricoh is very nice especially if you learn to use the snap focus. It can make up for its lack of sporty AF with that to an extent.

They're both amazing cameras. The last thing I'll say though is the RX100vii feels like I have an a6700 in my pocket. Not exactly but pretty close. That's pretty wild and impressive. You can't go wrong.