bitbucket支持镜像吗？

据我所知，没有拉镜，只有 智能镜 (在本地镜像远程存储库)

如果不是，“使用服务器推送更改”是从github备份所有回购的唯一方法吗？

是的，但它将是GitHub服务器，而不是您自己的服务器。

你可以用 actions/mirroring-repository

一个GitHub操作，用于将存储库镜像到GitHub、GitLab、BitBucket、AWS CodeCommit等上的另一个存储库。 这将复制所有提交、分支和标记。

示例，来自 问题3

# Deploy to BitBucket repos
name: Deploy to BitBucket Wordpress Repositories
# You may pin to the exact commit or the version.
# uses: pixta-dev/repository-mirroring-action@02f1627ade9e6b3b69e6a6d4fe8bc997474f48d1
# uses: pixta-dev/repository-mirroring-action@v1
  push:
    branches: [ master ]
  pull_request:
    branches: [ master ]
# A workflow run is made up of one or more jobs that can run sequentially or in parallel
jobs:
  # This workflow contains a single job called "build"
  deploy_to_test_repo:
    # The type of runner that the job will run on
    runs-on: ubuntu-latest
    # Steps represent a sequence of tasks that will be executed as part of the job
    steps:
      - uses: actions/checkout@v1