Hello @gfritz, Welcome to the /e/ users forum.
Fastboot is not the right tool for Samsung device…
What are possible OS running on your PC ?
Model: SM-P610
Region: DBT
Model name: SM-P610 / Galaxy Tab S6 Lite
Model full name: SM-P610NZAADBT
Country: Germany
Product date: 2020-04-24 00:00:00
Device age: 2155
KG Registered: NO
Info about Samsung Galaxy Tab S6 Lite (Wi-Fi) - gta4xlwifi
Install /e/OS on a Samsung Galaxy Tab S6 Lite (Wi-Fi) - “gta4xlwifi”