Swipe through your contacts. Keep the ones that matter.
Upload contacts file
.vcf · .csv · .xlsx · .xls
Loading contacts…
This becomes the Excel file name.
Open the Contacts app
Find it on your home screen
Tap "Lists" in the top-left
This shows all your contact groups
Long-press a list, tap "Export"
Hold down on the list name until a menu appears
Save to Files
In the share sheet, choose "Save to Files"
Come back here and upload!
Tap the upload area and select the .vcf file
Your contacts file will be saved in the Files app.
Pick it from there when uploading.
Alternative: iCloud Web