Anyone skate in the winter and if so, do you find it complimentary to cycling? Cardio is good, and I feel like the lower back, quads and hip flexors get a decent workout.

I don’t know the answer to your question but I recently move to a city with ice rinks and I am able to walk to one and skate tomorrow. It’s been about 4 years since the last time I laced up and I am looking forward to it.

Yup, Was skating fairly regularly and playing hockey, until my health issues, some 4 yrs ago.
Planning to get back 'on ice' tomorrow... , with my granddaughter... Will be an adventure - 1 st time in 4 yrs...
I found skating to be a great compliment to cycling, and visa-versa. And hockey certainly requires strong core and upper body strength as well.
One thing about hockey, which doesn't come into play as much with other forms of skating (speed, general putzing around...) is the load on the groin area is intense.
If you're doing hockey properly, you're at a 'sprint' most of the time on ice, with frequent directional changes, stops, hard starts and all that puts a huge load on the groin.
Can't say for figures...
Great cardio and muscular load on legs is very complimentary to cycling. Edge changes and driving the stride are great for balance; especially working the outside edge.
An Hour of good hard skating would be closely equivalent to riding an hour; and same light load on the joints.
I highly recommend Skating and XC (both 'Classic' and modern skate techniques) for anyone in the great White North or anyone who might have a rink within range.
Skate On
Yuri

I would imagine for those of us in warm climates, roller blading would be a suitable substitution for ice skating.

Anybody remember Beth and Eric Heiden?

The closest I come is occasionally skate skiing, which is much harder than cycling.

Not just "in the winter" since I frequent indoor rinks, but yes, I skate on occasion. I did so more about ten years ago, and got a bit back into it during the pandemic when I was working from home every day and could make lunchtime skating sessions.

Before the COVID lock-down, I was going to up to 7 speedskating practices a week.
In the distant past many bike races would come to speedskating practice in bad weather.
There are many world class competitors in both bike racing and speedskating.
It's more about aerobic and anaerobic training.