I don't think this will work because I want to remove the ContentFinderByUrl from the collection and replace it with mine... but I did try just in case...

I tried this:

public class CanonicalContentFinder : IContentFinder
{
    private readonly ILogger<CanonicalContentFinder> _logger;
    private readonly IRequestAccessor _requestAccessor;
    private readonly ContentFinderByUrl _finderByUrl;
    private readonly ContentFinderByIdPath _finderByIdPath;

    public CanonicalContentFinder(ILogger<CanonicalContentFinder> logger, 
        ILogger<ContentFinderByIdPath> loggerForFinderByIdPath,
        ILogger<ContentFinderByUrl> loggerForFinderByUrl,
        IOptions<Umbraco.Cms.Core.Configuration.Models.WebRoutingSettings> options,
        IRequestAccessor requestAccessor,
        IUmbracoContextAccessor umbracoContextAccessor,
        ContentFinderCollection cfc)
    {
        _logger = logger;
        _requestAccessor = requestAccessor;
        _finderByUrl = (ContentFinderByUrl)cfc.FirstOrDefault(x => x is ContentFinderByUrl);
        _finderByIdPath = (ContentFinderByIdPath)cfc.FirstOrDefault(x => x is ContentFinderByIdPath);
        //_finderByUrl = new ContentFinderByUrl(loggerForFinderByUrl, umbracoContextAccessor);
        //_finderByIdPath = new ContentFinderByIdPath(options, loggerForFinderByIdPath, requestAccessor, umbracoContextAccessor);
    }

with this composer (to make sure it hadn't removed the content finders I needed

public class DxpContentFindersComposer : IComposer
{
    public void Compose(IUmbracoBuilder builder)
    {
        builder.ContentFinders().InsertBefore<ContentFinderByUrl, CanonicalContentFinder>();
        //builder.ContentFinders().Remove<ContentFinderByUrl>();
        //builder.ContentFinders().Remove<ContentFinderByIdPath>();
        builder.ContentFinders().InsertAfter<CanonicalContentFinder, RedirectsContentFinder>();
        builder.SetContentLastChanceFinder<NotFoundContentFinder>();
    }
}

And I get this exception

InvalidOperationException: ValueFactory attempted to access the Value property of this instance.
System.Lazy<T>.ViaFactory(LazyThreadSafetyMode mode)
System.Lazy<T>.ExecutionAndPublication(LazyHelper executionAndPublication, bool useDefaultConstructor)
System.Lazy<T>.CreateValue()
System.Lazy<T>.get_Value()
Umbraco.Cms.Core.Composing.LazyReadOnlyCollection<T>.EnsureCollection()
Umbraco.Cms.Core.Composing.LazyReadOnlyCollection<T>.get_Value()
Umbraco.Cms.Core.Composing.LazyReadOnlyCollection<T>.GetEnumerator()
Umbraco.Cms.Core.Composing.BuilderCollectionBase<TItem>.GetEnumerator()
System.Linq.Enumerable.TryGetFirst<TSource>(IEnumerable<TSource> source, Func<TSource, bool> predicate, out bool found)
System.Linq.Enumerable.FirstOrDefault<TSource>(IEnumerable<TSource> source, Func<TSource, bool> predicate)
DXP.ContentFinders.CanonicalContentFinder..ctor(ILogger<CanonicalContentFinder> logger, ILogger<ContentFinderByIdPath> loggerForFinderByIdPath, ILogger<ContentFinderByUrl> loggerForFinderByUrl, IOptions<WebRoutingSettings> options, IRequestAccessor requestAccessor, IUmbracoContextAccessor umbracoContextAccessor, ContentFinderCollection cfc) in CanonicalContentFinder.cs
+
            _finderByUrl = (ContentFinderByUrl)cfc.FirstOrDefault(x => x is ContentFinderByUrl);
System.RuntimeMethodHandle.InvokeMethod(object target, object[] arguments, Signature sig, bool constructor, bool wrapExceptions)
System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, object[] parameters, CultureInfo culture)
...etc...