Using raw methods to query the Sitecore Content Search API using PowerShell.

PredicateBuilder-Attempt.ps1

Add-Type -AssemblyName "Sitecore.ContentSearch"
Add-Type -AssemblyName "Sitecore.ContentSearch.Linq"

class ExtendedSearchResultItem : Sitecore.ContentSearch.SearchTypes.SearchResultItem {
    [Sitecore.ContentSearch.IndexField("_latestversion")]
    [bool]$IsLatestVersion
}

# String
$methodContains = [string].GetMethod("Contains")

$method = [Sitecore.ContentSearch.Linq.Utilities.PredicateBuilder].GetMethod("True")
$type = [ExtendedSearchResultItem]
$genericMethod = $method.MakeGenericMethod($type)

$predicate = $genericMethod.Invoke([Sitecore.ContentSearch.Linq.Utilities.PredicateBuilder], $null)

$parameterItem = [System.Linq.Expressions.Expression]::Parameter([ExtendedSearchResultItem], "item")

$memberItem = [System.Linq.Expressions.Expression]::Property($parameterItem, "Name")
$constantItem = [System.Linq.Expressions.Expression]::Constant("avoid")
$bodyItem = [System.Linq.Expressions.Expression]::Equal($memberItem, $constantItem)
$predicateAnd = [System.Linq.Expressions.Expression]::Lambda($bodyItem, $parameterItem)

$predicate = [Sitecore.ContentSearch.Linq.Utilities.PredicateBuilder]::And($predicate, $predicateAnd)

$containsItem = [System.Linq.Expressions.Expression]::Call($memberItem, $methodContains, $constantItem)
$predicateAnd = [System.Linq.Expressions.Expression]::Lambda($containsItem, $parameterItem)

$predicate = [Sitecore.ContentSearch.Linq.Utilities.PredicateBuilder]::And($predicate, $predicateAnd)

PredicateBuilder-Attempt2.ps1

Add-Type -AssemblyName "Sitecore.ContentSearch"
Add-Type -AssemblyName "Sitecore.ContentSearch.Linq"

class ExtendedSearchResultItem : Sitecore.ContentSearch.SearchTypes.SearchResultItem {
    [Sitecore.ContentSearch.IndexField("_latestversion")]
    [bool]$IsLatestVersion
}

# String methods
$methodContains = [string].GetMethod("Contains")

# Build predicate
function New-PredicateBuilder {
    param(
        [string]$SearchType,
        [switch]$IsTrue
    )
    
    $methodName = @{$true="True";$false="False"}[$IsTrue.IsPresent]
    $type = Invoke-Expression -Command "[$($SearchType)]"
    $method = [Sitecore.ContentSearch.Linq.Utilities.PredicateBuilder].GetMethod($methodName)
    $genericMethod = $method.MakeGenericMethod($type)
    $genericMethod.Invoke([Sitecore.ContentSearch.Linq.Utilities.PredicateBuilder], $null)
}

$predicate = New-PredicateBuilder -SearchType "ExtendedSearchResultItem" -IsTrue

$parameterItem = [System.Linq.Expressions.Expression]::Parameter([ExtendedSearchResultItem], "item")

$memberItem = [System.Linq.Expressions.Expression]::Property($parameterItem, "Name")
$constantItem = [System.Linq.Expressions.Expression]::Constant("avoid")
$bodyItem = [System.Linq.Expressions.Expression]::Equal($memberItem, $constantItem)
$predicateAnd = [System.Linq.Expressions.Expression]::Lambda($bodyItem, $parameterItem)

#$predicate = [Sitecore.ContentSearch.Linq.Utilities.PredicateBuilder]::And($predicate, $predicateAnd)

#$containsItem = [System.Linq.Expressions.Expression]::Call($memberItem, $methodContains, $constantItem)
# = [System.Linq.Expressions.Expression]::Lambda($containsItem, $parameterItem)

$predicate = [Sitecore.ContentSearch.Linq.Utilities.PredicateBuilder]::And($predicate, $predicateAnd)

QueryIndex.ps1

Add-Type -AssemblyName "Sitecore.ContentSearch"
Add-Type -AssemblyName "Sitecore.ContentSearch.Linq"

class ExtendedSearchResultItem : Sitecore.ContentSearch.SearchTypes.SearchResultItem {
    [Sitecore.ContentSearch.IndexField("_latestversion")]
    [bool]$IsLatestVersion
}

function Get-Queryable {
    param(
        [Sitecore.ContentSearch.IProviderSearchContext]$Context,
        [string]$SearchType
    )
    
    $method = $context.GetType().GetMethods() | Where-Object { $_.Name -eq "GetQueryable" } | Select-Object -First 1
    $type = Invoke-Expression -Command "[$($SearchType)]"
    $genericMethod = $method.MakeGenericMethod($type)
    ,$genericMethod.Invoke($context, $null)
}

$searchIndex = [Sitecore.ContentSearch.ContentSearchManager]::GetIndex("sitecore_master_index")
$results = New-UsingBlock ($context = $searchIndex.CreateSearchContext()) {
    $queryable = Get-Queryable -Context $context -SearchType "ExtendedSearchResultItem"
    #$queryable = [Sitecore.ContentSearch.Utilities.DynamicQueryable]::Where($queryable, "TemplateName = @0", @("News Article"))
    $templateId = [Sitecore.Data.ID]::Parse("{A3194703-25ED-4722-8744-4C35190DA9DD}")
    $name = "avoid-"
    $queryable = [Sitecore.ContentSearch.Utilities.DynamicQueryable]::Where($queryable, "TemplateId = @0 And Name.Contains(@1) And IsLatestVersion = @2", @($templateId, $name, $true))
    #$queryable = [Sitecore.ContentSearch.Utilities.DynamicQueryable]::Take($queryable, 100)
    $queryable
}

$results | Select-Object -Property Name,IsLatestVersion