在Angular 8中实现动态路由上的SEO图片和内容，可以通过以下步骤来解决：

1. 首先，确保你的Angular应用已经安装了@angular/platform-server模块。如果没有安装，可以通过以下命令来安装：

npm install @angular/platform-server --save

2. 创建一个名为"server.ts"的文件，并在其中添加以下代码：

import 'zone.js/dist/zone-node';
import 'reflect-metadata';
import { enableProdMode } from '@angular/core';
import { renderModuleFactory } from '@angular/platform-server';
import { provideModuleMap } from '@nguniversal/module-map-ngfactory-loader';
import { readFileSync } from 'fs';
import { join } from 'path';
import * as express from 'express';

enableProdMode();

const app = express();
const distFolder = join(process.cwd(), 'dist/browser');
const indexHtml = readFileSync(join(distFolder, 'index.html'), 'utf8');
const { AppServerModuleNgFactory, LAZY_MODULE_MAP } = require('./dist/server/main');

app.engine('html', (_, options, callback) => {
  const opts = { document: indexHtml, url: options.req.url };

  renderModuleFactory(AppServerModuleNgFactory, {
    document: indexHtml,
    url: options.req.url,
    extraProviders: [
      provideModuleMap(LAZY_MODULE_MAP)
    ]
  })
  .then(html => callback(null, html));
});

app.set('view engine', 'html');
app.set('views', distFolder);
app.get('*.*', express.static(distFolder, {
  maxAge: '1y'
}));
app.get('*', (req, res) => {
  res.render('index', { req });
});

app.listen(4000, () => {
  console.log('Angular Universal Node Express server listening on http://localhost:4000');
});

3. 在"angular.json"文件中的"architect"部分的"build"配置中，添加以下内容：

"architect": {
  "build": {
    "options": {
      ...
      "outputPath": "dist/browser",
      "index": "src/index.html",
      ...
    },
    ...
  },
  "server": {
    "builder": "@angular-devkit/build-angular:server",
    "options": {
      "outputPath": "dist/server",
      "main": "src/main.server.ts",
      "tsConfig": "src/tsconfig.server.json"
    },
    ...
  }
}

4. 创建一个名为"main.server.ts"的文件，并在其中添加以下代码：

export { AppServerModule } from './app/app.server.module';

5. 在"tsconfig.json"文件中，添加以下配置：

"compilerOptions": {
  ...
  "module": "commonjs",
  "types": ["node"],
  ...
}

6. 在"app.module.ts"文件中的@NgModule装饰器中，添加以下代码：

import { NgModule, APP_INITIALIZER } from '@angular/core';
...
import { Meta, Title } from '@angular/platform-browser';

export function initializeApp(meta: Meta, title: Title) {
  return () => {
    title.setTitle('My App');
    meta.addTags([
      { name: 'description', content: 'My App Description' },
      { property: 'og:title', content: 'My App' },
      { property: 'og:description', content: 'My App Description' },
      { property: 'og:image', content: 'https://example.com/my-app-image.jpg' },
      { name: 'twitter:title', content: 'My App' },
      { name: 'twitter:description', content: 'My App Description' },
      { name: 'twitter:image', content: 'https://example.com/my-app-image.jpg' }
    ]);
  };
}

@NgModule({
  ...
  providers: [
    ...
    {
      provide: APP_INITIALIZER,
      useFactory: initializeApp,
      deps: [Meta, Title],
      multi: true
    }
  ],
  ...
})

7. 更新"server.ts"文件中的"provideModuleMap"提供者，以使用"server/main"而不是"main"：

const { AppServerModuleNgFactory, LAZY_MODULE_MAP } = require('./dist/server/main');

8. 在命令行中运行以下命令来构建和启动Angular应用：

ng build --prod
node server.js

这样就完成了在Angular 8动态路由上实现SEO图片和内容的解