Power Outdoors

So far I’ve only been using Xert with my indoor smart trainer; do I need to have a powermeter for using Xert outdoors (and having it taking in the data properly) or can it get sufficient info from my Edge 1030 to interpolate as required?

If you are capturing HR you can enable this —
Heart Rate Derived Metrics – Xert (baronbiosys.com)

However, the preferred solution is to add a power meter to your bike.
When you enable HRDM Xert uses historical data to calculate XSS.
Since you only have smart trainer data the results will be biased towards that data set.
Outdoor power data is often different than indoors in various ways, most notably peak power but also other points along your power curve. Road bike data is also different than off-road activity.
If you want the most out of Xert you’ll want to add a power meter to your bike.
A 4iiii or Stages left crank meter is one of the least expensive ways to do that.

Thanks for that.