Hello Pandi Vijayaraj,
As you mentioned, most i.MX8 boards on the market, both NXP’s and from third-parties use micro SD cards and do not come with a full size SD card slot. All boards I’ve seen from Boundary Device, iWave, Variscite and Toradex use the microSD alternative.
The only exception I’ve seen so far would be Phytec. Their phyCORE-i.MX 8M is listed as having a regular SDIO port. I would recommend double checking with them which board or carrier boards have this feature just to be sure before ordering.
https://www.phytec.in/product/system-on-modules/phycore-imx-8m/
My apologies for the inconvenience.
Regards,