A Lexar SDXC card with 1TB capacity was presented at the CES -- with immediate availability. This makes it the largest SD card currently available, after the 1TB Sandisk card shown in 2016 has still not been released.
However, the Lexar UHS-I card is not characterized by maximum speed, because the top writing speed of the Class 10 certified card with U3 / V30 rating is up to 70MB/s (reading speed up to 95MB/s, 633x). However, "only" a maximum of 30MB/s is guaranteed throughout. This is sufficient for many 4K applications, but there are already UHS II SDXC cards with V60 or V90 rating, which write 60 or 90 MB/s continuously and are therefore also 8K-capable (but again do not accept 1 TB).
The 1TB Lexar Professional 633x SDXC UHS-I card is now available for 499.99 dollars. Behind the Lexar brand is the Chinese flash memory manufacturer Longsys.