I has to be the Finnish Gauss-Krüger zone 25 https://epsg.org/crs_3879/ETRS89-GK25FIN.html?
So nothing that is specific to Trimble. The Trimble logo stands at the corner just because they seem to use Trimble services for the web map https://upa.trimble.com/en-eu.
You can convert the coordinates with your favorite software.
Example with gdaltransform https://gdal.org/programs/gdaltransform.html
gdaltransform -s_srs epsg:3879 -t_srs epsg:4326
Enter X Y [Z [T]] values separated by space, and press Return.
25485308 6675757
24.7351469525604 60.1943627146485 0
Notice that for gdaltransform you must change the order of North (P) and East (I) coordinates. The result in EPSG:4326 is printed in longitude-latitude order.