Display Raspberry Pi serial number using standard command-line utilities.

Display model using sysfs.

$ cat /sys/firmware/devicetree/base/model; echo
Raspberry Pi 4 Model B Rev 1.4

Display serial number using sysfs.

$ cat /sys/firmware/devicetree/base/serial-number; echo
100000000bc0a195

Alternatively, use procfs to get this information.

$ cat /proc/cpuinfo 
processor       : 0
model name      : ARMv7 Processor rev 3 (v7l)
BogoMIPS        : 108.00
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xd08
CPU revision    : 3

processor       : 1
model name      : ARMv7 Processor rev 3 (v7l)
BogoMIPS        : 108.00
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xd08
CPU revision    : 3

processor       : 2
model name      : ARMv7 Processor rev 3 (v7l)
BogoMIPS        : 108.00
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xd08
CPU revision    : 3

processor       : 3
model name      : ARMv7 Processor rev 3 (v7l)
BogoMIPS        : 108.00
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xd08
CPU revision    : 3

Hardware        : BCM2711
Revision        : d03114
Serial          : 100000000bc0a195
Model           : Raspberry Pi 4 Model B Rev 1.4

Simple as that.