I came up with a solution for anyone who finds this in the future. My solution involves creating 2 custom url providers that inherit the default providers; a provider inherited from DefaultUrlProvider and DefaultMediaUrlProvider. You need to register these providers with Umbraco builder in startup.

For my implementation, I look for a query string in the current Uri and then change the UrlMode to Absolute if the value is true. This results in every link and image to render with an absolute URL.

public class CustomMediaUrlProvider : DefaultMediaUrlProvider
{
    public CustomMediaUrlProvider(MediaUrlGeneratorCollection mediaPathGenerators, UriUtility uriUtility)
        : base(mediaPathGenerators, uriUtility)
    {
    }

    public override UrlInfo GetMediaUrl(IPublishedContent content, string propertyAlias, UrlMode mode, string culture, Uri current)
    {
        var query = HttpUtility.ParseQueryString(current.Query);

        if (bool.TryParse(query["absoluteUrls"], out bool results) && results == true)
        {
            mode = UrlMode.Absolute;
        }

        return base.GetMediaUrl(content, propertyAlias, mode, culture, current);

    }
}


public class CustomUrlProvider : DefaultUrlProvider
{
    private readonly IHttpContextAccessor _httpContextAccessor;

    public CustomUrlProvider(IOptionsMonitor<RequestHandlerSettings> requestSettings, ILogger<DefaultUrlProvider> logger, ISiteDomainMapper siteDomainMapper, IUmbracoContextAccessor umbracoContextAccessor, UriUtility uriUtility, ILocalizationService localizationService, IHttpContextAccessor httpContextAccessor)
        : base(requestSettings, logger, siteDomainMapper, umbracoContextAccessor, uriUtility, localizationService)
    {
        _httpContextAccessor = httpContextAccessor;
    }

    public override UrlInfo GetUrl(IPublishedContent content, UrlMode mode, string culture, Uri current)
    {
        var query = HttpUtility.ParseQueryString(current.Query);

        if (bool.TryParse(query["absoluteUrls"], out bool results) && results == true)
        {
            mode = UrlMode.Absolute;
        }

        return base.GetUrl(content, mode, culture, current);
    }
}

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