Search different string from multiple records

I suggest making a table to import the full excel sheet into. Import the sheet to create the columns so that way they will match up perfectly for future imports.

Set the key field to be the serial number 

Then make a relationship where Excel import entry has many GPS tracker. Let it create a field for Related Excel Import, but then change that field to be a formula equal to the serial.  Make a formula checkbox field with a value of true called [Excel import exists?]

Lookup [Excel import exists?] down to GPS tracker and use that as a Dynamic fFlter to filter the GPS Trackers with serial in that table.

When you get a new serial number list, just delete out all the records in that excel table and import them again. If you want to make it more convenient for your users, there are ways to have an admin type record where you could make a button to purge the table and you could make another button to land the user on that import window just sort of dumb things down if you have the luxury of an admin person being able to do this on your behalf.  Or maybe you are your own admin person and you just want to dumb it  down for yourself.