move shopware content of different versions

I want to migrate a shopware with shopware 3.5.4 version to shopware 5 version, but I cannot update it. I'm also trying to transfer its contents and theme to shopware 5, which I just installed. Is there a short way I can do this

As most old versions of shopware (at least the ones I got to know) are pretty "tinkered", the easy way moving to recent shopware is:

1. Copy database and local files to a supporting host (keep in mind that you will need older versions of PHP)
2. Disable (better uninstall) every plugin and theme, switch to default theme
3. Upgrade to SW4, then upgrade to recent version of shopware 5 by following this guide strictly https://docs.shopware.com/de/shopware-5-de/update-guides
4. Use import/export tool to export all product and order data

You might as well succeed by skipping step 3, applying all db-migrations, and using the db with your fresh installation, but I guess you will run into trouble with your media files (images etc. might not be usable anymore).

Another way might be writing a small script to export all data to csv and import it with the native tool.

There is no way (that I know of) to make your old theme working in recent versions of SW5. Before creating a new one, keep in mind SW5 will quite soon be EOL, and SW6 is much faster and way ahead in usability. You could use SW6's import functions to move from SW5 to the recent release.