<trkpt lat="x" lon="y">
<ele>56.72105575919558</ele>
<extensions>
<speed>1.8200000524520874</speed>
<wstxns2:TrackPointExtension xmlns:wstxns2="gpxtxp"/>
</extensions>
<time>2024-02-28T09:28:26Z</time>
</trkpt>
So it contains speed (average since previous point), elevation, location and time (offtopic: it took me a while to understand that this elevation is not the actual elevation above sea level; only yesterday I figured that out and fixed it in the code!).