For my blazor library which is a modification of this awesome library I have to convert an ExpandoObject into a Dictionary<string, object> since ExpandoObjects aren't serialized properly in the newest preview versions of dotnet-core. See my question related to this for more details.

My current approach goes as follows:

private static Dictionary<string, object> ConvertDynamicToDictonary(IDictionary<string, object> value)
{
    return value.ToDictionary(
        p => p.Key,
        p =>
        {
            // if it's another IDict (might be a ExpandoObject or could also be an actual Dict containing ExpandoObjects) just go through it recursively
            if (p.Value is IDictionary<string, object> dict)
            {
                return ConvertDynamicToDictonary(dict);
            }

            // if it's an IEnumerable, it might have ExpandoObjects inside, so check for that
            if (p.Value is IEnumerable<object> list)
            {
                if (list.Any(o => o is ExpandoObject))
                {
                    // if it does contain ExpandoObjects, take all of those and also go through them recursively
                    return list
                        .Where(o => o is ExpandoObject)
                        .Select(o => ConvertDynamicToDictonary((ExpandoObject)o));
                }
            }

            // neither an IDict nor an IEnumerable -> it's probably fine to just return the value it has
            return p.Value;
        } 
    );
}

This works fine but I'm not sure about the IEnumerable part. If I omit the list.Any check it still works fine. New version (only write the IEnumerable part changed):

// if it's an IEnumerable, it might have ExpandoObjects inside, so check for that
if (p.Value is IEnumerable<object> list)
{
    // take all ExpandoObjects and go through them recursively
    return list
        .Where(o => o is ExpandoObject)
        .Select(o => ConvertDynamicToDictonary((ExpandoObject)o));
}

I have also tried using IEnumerable<ExpandoObject> instead of just IEnumerable<object> to see if that would work and maybe be cleaner and I can confirm that that does not work (throws error).

What I would like to know now is, if it's a good idea to omit the Any check and which option is more performant (and why) and/or cleaner.
Also please mention every small thing that bugs you, I always want to make it as perfect as possible :)

I first wanted to post this on StackOverflow but I think it fits better on here - correct me if I'm wrong.

EDIT 0:
This function is only called from inside the library and already marked private static. I simply forgot to put that the first time, this is now corrected.
This answer suggests changing it into a extension method. Would this still be the "correct" way of doing it, now that it's clear that the method is not supposed to be called outside of the library itself?