Base Lightning Web Components can be utilised in open source LWC-based applications produced on the Heroku platform or elsewhere, but not all of them. At Trailhead, you can learn more about LWC OSS.
Other aspects of the Lightning Web Component ecosystem, on the other hand, are exclusive to the Salesforce platform. You can't import from @salesforce/apex, for example, in LWC OSS. When you're not deploying code and metadata in your org, you won't be able to import from modules like @salesforce/schema, which offers schema details for your org.
If you need to communicate with the organisation, you'll need to set up your own API connection and make all of the calls yourself.