The Denon s740h only has outputs for the subwoofer, so going from the receiver to Sonos seems impossible. But going from Sonos to the Denon s740h, you have the option of connecting the line out of the Port to the Media Player in on the Denon. 

Is there a way to get Sonos and my other speakers working at the same time from Denon? Do you have any YouTube videos on this topic?

You can group the other rooms FROM the Port, since that is the main speaker/device connected to the Denon:

https://support.sonos.com/en-us/article/group-and-ungroup-rooms

What exactly do you want to achieve? Do you want the same music to play on the Denon and the Sonos surround set up? Or do you want to somehow combine the Denon and the Sonos surround set up in one physical room? I would advise against the last option.

Latter, combine Sonos and d Denon system in one physical room

It’s not possible to group the audio FROM the Denon with your Sonos speakers. There are ONLY line level Sub outputs on the Denon.

you can however group the audio from your Sonos speakers with the Denon through a Port. There are two line level inputs you can use to connect the line out on the Port.

What porting device do you recommend to make this happen?

This one..:

https://support.sonos.com/en-us/article/set-up-your-sonos-port

Hi ​@Sean7885 

Welcome to the Sonos Community!

Your Sonos Arc Ultra is designed to replace an AV receiver, not to work along with one.

You have not stated what it is exactly that you are trying to achieve, but whatever it is, there’s a good chance that it is not possible.

The suggestions provided above all involve a Port - a Port only deals with stereo audio, and it will induce a minimum delay of 75ms when doing so, in either direction (assuming you try to play TV audio).

I hope this helps.