A low-profile compact 8-port MIMO (8PM) antenna module based on using four modified dual-polarized patch antennas is presented for six-generation (6G) mobile device MIMO featuring 8 spatial streams. The 8PM antenna module can provide 8 uncorrelated waves in the promising new international mobile telecommunication spectrum of 6.425-7.125 GHz for 6G applications, yet having a low profile of 1 mm ( $0.021\lambda $ at 6.425 GHz) and a small area of 36 mm $\times36$ mm ( $0.77\lambda \times 0.77\lambda $ or $0.59\lambda ^{2}$ at 6.425 GHz). That is, the 8PM antenna module is equivalent to have 8 MIMO antennas densely integrated into a compact structure with each antenna occupying a small area of $0.074\lambda ^{2}$ . With a compact size, the 8PM antenna module or even its $1\times2$ array is easy to be embedded in the narrow backcover region of the modern smartphone. The $1\times2\,\,8$ PM antenna module array can provide 16 receive antennas in the mobile device for the $16\times8$ MIMO system with 8 spatial streams. With an extreme or a much larger number of the receive antennas than that of the spatial streams (extreme receive antennas-aided MIMO), the MIMO system can support a high signal modulation up to 1024 QAM (10 bits per symbol) so that a high spectral efficiency of larger than 56 bps/Hz is obtained. That is, with only 200 MHz bandwidth, the user can experience a data throughput of larger than 10 Gbps. Design considerations of the 8PM antenna module are addressed. Its $1\times2$ array is also fabricated and tested in the $16\times8$ MIMO system. Results of the fabricated module array and the $16\times8$ MIMO system testing are presented.