thank you for any input:)

But, with a 30-nch NXR, an OTR might not be great, but there are numbers of folks here who have done okay with them. I definitely would look at 400 cfm units and would look at mounting it has highw above the stove-top as is practical. Nunyabiz has posted here about this subjct. I believe the link below will show you nunyabiz's set-up with his/her/their NXR and OTR.

Do a search on "OTR + NXR" and you will find a number of threads.

I don't think I have ever seen a OTR with more than 400cfm and at the time I bought mine it was the only one that had 400cfm that I could find.
I would NOT use any less than 400CFM for sure.

It works fine but it will get a bit overwhelmed if I start cooking several slices of bacon and 6 eggs on my 2 burner griddle plus the other 2 burners going with what ever and biscuits in the oven.
Best would be a minimum of 600CFM ventilation hood vented outside, BUT that is NOT "required" certainly not for a 30".

36" and yeah you can forget about using ANY OTR.

We have ours vented inside through the internal charcoal filter and except for a very few occasions it does the job adequately.
For us a proper 600+ CFM ventilation hood vented outside would have more than doubled the price of the range so was out of the question, not to mention we would also have no place for a microwave.

We bought the LG LMHM2017ST
which 17 months ago cost us $395.61 shipped to the door.

It has been a great microwave, no issues, lots of power and options, great "warming feature" and I think the best ventilation on any OTR microwave.
It is also nice to have the controls on the bottom of the door on a OTR.

"Ideally" in a perfect world and if money were no object you should use roughly 1CFM per each 100BTU.
The NXR puts out 82,000BTU with everything blasting, so 820CFM vented outside with the fan outside using at least a 1000CFM rated squirrel cage blower which should give around 800CFM at the hood.
17 months ago that would have cost us around $1800 installed.
That is what we paid for the range.

I've had a 300 cfm OTR since moving into this house, 8 years ago. Until last month, it was always internally vented, and quite frankly, the venting was a joke. Anything remotely smoky and the vent was immediately overwhelmed.

I paid a handyman a few hundred last month to install an external vent. My range is on a external wall, so there isn't a lot of turns and twists or extensive demo that had to be done. He basically measured, drilled a hole through the cabinet, drilled a matching hole through the siding, and hooked up the vent tubing (I'm sure there's a technical term for that but I have no idea what it is.)

The difference is night and day. Sure, it could be better if the vent was a 900 cfm vent, but...in MN, make up air is required for anything over 300 cfm, and that's not an expense I want right now. I purposefully cooked something that I knew would set off the fire alarms pre-external venting the night it was installed. No fire alarms. Smoke in the kitchen was very minimal.

I really wish I had looked into this years ago instead of assuming it would be thousands of $$$. I suggest you look into it before you dismiss it.