I can save you some of that research. The KeePass family of password managers are open source and based around a shared file format. They save your passwords in an encrypted file on your computer or phone’s local drive. An ecosystem of apps by different people can parse that file format (after you enter your master password), and at least one app can export as CSV or HTML, so migration is not a problem.

Since your passwords are in a local file, there is no online password manager that can be hacked. If you worry that your local password manager software will have malicious updates posted, you only have to read news at the time you download an update, which can be as infrequent as you like.

If you need to share passwords among your devices, you can store the encrypted file in a generic file syncing service such as Google Drive or Dropbox. Those services are less of a target for hackers than dedicated password managers, and even if someone obtains that file, your passwords will be safe as long as your master password is strong.

Specific KeePass clients I recommend: https://keepassxc.org/ on desktop, https://github.com/PhilippC/keepass2android on Android.