The new Galaxy tablet to get the One UI 6 version is the Galaxy Tab S8. It includes Galaxy S8 5G, Galaxy Tab S8+ & Galaxy Tab S8 Ultra tablets. The new firmware is X906BXXU5CWK7 and it comes with a November security patch. The file size is really huge, and you need a Wi-Fi connection to download it.
It is available in Europe including Poland, Germany & the UK. One UI 6 has already been seeded on the Galaxy Tab S9 series.