Manage function (or table) parameters in Navigation Table

Hello,

I'm trying to add parameters to API calls. OAuth is working and I can generate a list of available datasets in a dynamic navigation table:

Here is the auth screen with no optional parameters, the one I want to appear in the screenshot above (in the right pane):

Now I can't figure out how to allow date and dimension parameters and show on right pane (the one showing error, since dates and dimensions are null).

I read the whole TripPin walkthrough several times to end up at this point, but I'm getting lost about parameters and navigation table...

Here is some relevant code:

[DataSource.Kind="PQ_SearchConsole", Publish="PQ_SearchConsole.Publish"]
shared PQ_SearchConsole.Contents = Value.ReplaceType(CreateNavTable, contentsType);
contentsType = type function (
    optional start as (type text meta [
        Documentation.FieldCaption = "Début",
        Documentation.FieldDescription = "Date de début de l'extraction (les mots clés sont autorisés : `today`, `yesterday`, `60daysAgo`).",
        Documentation.SampleValues = {"2022-01-01"}
    ]),
    optional end as (type text meta [
        Documentation.FieldCaption = "Fin",
        Documentation.FieldDescription = "Date de fin de l'extraction (les mots clés sont autorisés : `today`, `yesterday`, `60daysAgo`).",
        Documentation.SampleValues = {"yesterday"}
    ]),
    optional params  as (type nullable text meta [
        Documentation.FieldCaption = "Dimensions",
        Documentation.FieldDescription = "Saisir les dimensions souhaitées",
        Documentation.SampleValues = {"query,page,device,country"}
    ])

) as table [...]

CreateNavTable = (
    optional start as text, 
    optional end as text, 
    optional params as nullable text
) as table => 
    let
        sites = GetSitesList(),
        navBody = List.Accumulate( sites[siteUrl], {}, (state, current)=> state &
            {{current, current, PQ_SearchConsole.GetContents(current,start,end,params), "Function", "Function", true}}
        ),

        navHeader = {"Name","Key","Data","ItemKind", "ItemName", "IsLeaf"}, 
        objects = #table(navHeader, navBody),
        NavTable = Table.ToNavigationTable(objects, {"Key"}, "Name", "Data", "ItemKind", "ItemName", "IsLeaf")
    in
        NavTable

GetSitesList = () as table => 
    let
        source = Json.Document( Web.Contents ( api_base_uri ) ),
        sites = Table.FromRecords( source[siteEntry], type table[siteUrl = Text.Type /*, permissionLevel = Text.Type*/] )
    in
        sites;

PQ_SearchConsole.GetContents = (
    website as text,
    start as text, 
    end as text, 
    params as nullable text
)  =>
    let 
        now =  DateTime.FixedLocalNow(), 

        reqStartDate = Date.From(dateFunc(start)), // #date( Date.Year(now), Date.Month(now) - 1 , Date.Day(now) ),
        reqEndDate = Date.From(dateFunc(end)), //  #date( Date.Year(now), Date.Month(now), Date.Day(now) ),
        reqDimensions = if params="" or params = null then {} else Text.Split(params,","),
        source = Web.Contents( api_base_uri, [
            RelativePath = Text.Combine({Uri.EscapeDataString(website), "/searchAnalytics/query"}), 
            Headers = [#"Content-Type"="application/json"],
            Content = Json.FromValue([startDate = reqStartDate, endDate = reqEndDate, dimension = reqDimensions]) 
        ]),
        report = Json.Document(source)
    in
        report