My 87 year old grandma's computer wouldn't boot. We set her up on a new laptop. But we couldn't remember her Gmail password. We never recovered her account, including any photos backed up to Google Photos.
You should be able to image her hard disk, and probably boot it up in a VM. Windows activation might complain in that case, but her data will be there.
Is that still an option? I haven't used Windows for a long time, but I believe Microsoft has been pushing towards enabling BitLocker by default for everyone. If you don't have the BitLocker recovery key, or access to the user's Microsoft cloud account (which AFAIK has a copy of the BitLocker recovery key), the only way to decrypt the hard disk is to boot the system the normal way (with SecureBoot enabled even), since the key is held on the TPM.