Under PowerShell, Get-Command will find executables anywhere in $Env:PATH.
$ Get-Command eventvwr
CommandType   Name          Definition
-----------   ----          ----------
Application   eventvwr.exe  c:\windows\system32\eventvwr.exe
Application   eventvwr.msc  c:\windows\system32\eventvwr.msc
And since powershell let's you define aliases, which can be defined like so.
$ sal which gcm   # short form of `Set-Alias which Get-Command`
$ which foo
...
PowerShell commands are not just executable files (.exe, .ps1, etc). They can also be cmdlets, functions, aliases, custom executable suffixes set in $Env:PATHEXT, etc. Get-Command is able to find and list all of these commands (quite akin to Bash's type -a foo). This alone makes it better than where.exe, which.exe, etc which are typically limited to finding just executables.
Finding executables using only part of the name
$ gcm *disk*
CommandType     Name                             Version    Source
-----------     ----                             -------    ------
Alias           Disable-PhysicalDiskIndication   2.0.0.0    Storage
Alias           Enable-PhysicalDiskIndication    2.0.0.0    Storage
Function        Add-PhysicalDisk                 2.0.0.0    Storage
Function        Add-VirtualDiskToMaskingSet      2.0.0.0    Storage
Function        Clear-Disk                       2.0.0.0    Storage
Cmdlet          Get-PmemDisk                     1.0.0.0    PersistentMemory
Cmdlet          New-PmemDisk                     1.0.0.0    PersistentMemory
Cmdlet          Remove-PmemDisk                  1.0.0.0    PersistentMemory
Application     diskmgmt.msc                     0.0.0.0    C:\WINDOWS\system32\diskmgmt.msc
Application     diskpart.exe                     10.0.17... C:\WINDOWS\system32\diskpart.exe
Application     diskperf.exe                     10.0.17... C:\WINDOWS\system32\diskperf.exe
Application     diskraid.exe                     10.0.17... C:\WINDOWS\system32\diskraid.exe
...
Finding custom executables
Unlike UNIX, where executables are files with the executable (+x) bit set, executables on windows are files present in one of the directories specified in the $PATH env. variable whose filename suffixes are named in the $PATHEXT env. variable (defaults to .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC;.CPL).
As Get-Command also honours this env. variable, it can be extended to list custom executables. e.g.
$ $Env:PATHEXT="$Env:PATHEXT;.dll;.ps1;.psm1;.py"     # temporary assignment, only for this shell's process
$ gcm user32,kernel32,*WASM*,*http*py
CommandType     Name                        Version    Source
-----------     ----                        -------    ------
ExternalScript  Invoke-WASMProfiler.ps1                C:\WINDOWS\System32\WindowsPowerShell\v1.0\Invoke-WASMProfiler.ps1
Application     http-server.py              0.0.0.0    C:\Users\ME\AppData\Local\Microsoft\WindowsApps\http-server.py
Application     kernel32.dll                10.0.17... C:\WINDOWS\system32\kernel32.dll
Application     user32.dll                  10.0.17... C:\WINDOWS\system32\user32.dll
See Get-Command for more options and examples.