Hello Whitefish73,
Thank you for reaching out in Apple Support Communities. We noticed you were reviewing this article: If you can't reset your Mac login password Were you able to follow the section that says, "Start up from macOS Recovery" and follow the next sections within the article to help reset the password? If not, we recommend for you to continue through the rest of the article to see if that helps you to sign in under your user account. Here are the steps you'll want to follow from the article you were reviewing:
If you're asked to select an admin user
If you're asked to select an admin user you know the password for, click “Forgot all passwords?” and proceed as described below.
If you're asked for your Apple ID information
Enter your Apple ID information. You might also be asked to enter the verification code sent to your other devices.
If you see an Activation Lock window, click Exit to Recovery Utilities. Then continue as described in the next section, “Use the Reset Password assistant.”
If you're asked to select a user that you want to reset the password for:
1. Select the user, then enter your new password information and click Next.
2. When authentication has succeeded, click Exit.
3. Choose Apple menu > Restart. Password reset is now complete, so you don't need to take additional steps.
If you're asked for your recovery key
1. Enter your FileVault recovery key. You received it when you turned on FileVault and chose to create a recovery key instead of allowing your iCloud account (Apple ID) to unlock your disk.
2. When prompted to reset your password, click Reset Password.
3. Select a user to reset the password for.
4. After successfully authenticating, click Exit.
5. Choose Apple menu > Restart. Password reset is now complete, so you don't need to take additional steps.
These steps are outlined here: If you can't reset your Mac login password
If these steps do not help, please continue to the next section that says "Use the Reset Password assistant." There's additional steps within that section to help you reset the password.
Kind regards.