Hi tschlar,
Sorry for your loss.
The article you linked appears to be related to getting data from your sister's Apple ID. If you only want to reuse the devices and not her Apple ID, you can erase those devices via these steps:
How to erase her iPhone and iPad: If you forgot your iPhone passcode - Apple Support (CA)
How to erase her Mac (select the appropriate article, depending on the processor):
How to erase an Intel-based Mac - Apple Support (CA)
How to erase a Mac with Apple silicon - Apple Support (CA)
How to reinstall macOS - Apple Support (CA)
After erasing the iPhone and iPod (possibly the Mac as well), you might run into Activation Lock (the device might require your sister's Apple ID and password). If this is the case, you can ask Apple to delete your sister's Apple ID and remove Activation Lock at the Digital Legacy portal. You'll need proof of death documents in order for Apple to proceed.