Garmin does not support "native" power. The only way to get it, either with Stryd or with Garmin's own pod, is by installing the Connect IQ data field, and you can't use Connect IQ data for preprogrammed workouts. It has long been speculated that Garmin will add native power support at some point.
One option is to do a structured workout without specifying the power targets. In that case, you'd just have to remember your target and glance at your watch periodically.
Otherwise, you have to switch to something other than Garmin. The new Coros Pace 2 does structured running power workouts, and it doesn't even require a pod, though you can use Stryd if you want to. Suunto and Polar also support native running power.
One thing to keep in mind is that your power numbers will be different if you switch hardware. Everyone calculates running power a bit differently. I won't go down the rabbit hole of what running power really is right now, but suffice it to say that all of the options on the market now are pretty good. They correlate with oxygen consumption, which is what matters. You will just have to recalibrate what your numbers mean if you switch to different tech.