What characters can I use for access and Excel passwords?

It's not primary, it's not consistent enough, but there's an article like this.

This is the only Microsoft document that is case sensitive and can be up to 15 characters long.
Protect a document with a password

Passwords are case-sensitive and can be a maximum of 15 characters long.

This is Microsoft's documentation, but it's a policy article, and it's not about specific character types.
Password policy recommendations for Office 365

Office 365 Username, Password Requirements|Your Office 365 Best Recipe

Double-check Office 365 username and password for characters.
This is basically the same as AzureAD username and password requirements.

Password

• Use 3 out of 4 types below
  • A–Z
  • a–z
  • 0–9
  • @#$%^&* –_!+=[] { } | \ : ‘ , . ? / `~`();
• 8 to 256 characters
• The previous password you changed is not available

• A–Z
• a–z
• 0–9
• @#$%^&* –_!+=[] { } | \ : ‘ , . ? / `~`();

Note: Azure Active Directory Password Policy and Limitations
Note: Password policies and restrictions in Azure Active Directory
Note: Please note that the email address rule system summary is all wrong

Office 365 User Information Character Limitations|SECIOSS

3.Office 365 Password

You must include at least three of the following four types, ranging from 8 characters to 16 characters.

• Capital letters (A-Z)
• Small Characters (a-z)
• Number (0-9)
• The following symbols: !@#$%^&*-_+=[ ] { } | \ : ' , . ? / `~"();<>

Sec If SeciosLink is single sign-on, the user password policy will follow secioslink, but the password for the office365 administrative account will be the office365 password policy.
*For Yamagata parentheses [<] and [>], only the Windows PowerShell command setting is valid.
UnCannot contain Unicode characters, spaces, user name (user ID) aliases (before @).

EXCEL Password ProtectionAvailable Characters|OKWAVE>PC Smartphone>Software>Excel

Try entering a string containing hiragana and kanji in the appropriate cell, then copy the string with kanji and paste it into the password entry field to set the password.

Abbreviated

This means that only alphanumeric characters (a-z, 0-9) and !, @, #, $, % , ~, & *, (,), +, = are allowed.
Also, please note that even if you say ..., only half-width characters are allowed and full-width characters are not allowed.

By the way, alphanumeric characters (a-z, 0-9) are probably incorrect alphanumeric characters (A-Z, a-z, 0-9)

Verified the "Read Password" in the xlsx file in the latest Microsoft 365 Offline Office Excel (version 2112 build 14729.20260).

• You could only enter 255 characters.
• ASCII printable characters (U+0020 to U+007E, note that spaces are also included) were successful.
• If you have characters other than ASCII printable characters, such as hiragana or full-width alphanumeric characters, the following warning was displayed, but you could use them.

  The password contains characters that cannot be properly translated into the Microsoft Excel Macintosh version.We recommend that you use alphanumeric characters (a-z, 0-9) and symbols (!, @, #, $, %, ^, &, *, (,), +, =) for passwords.

• UTF-16 can also use U+10000 or later as a surrogate pair, but it can be two characters long (two characters with "**").(For example, "good" U+5409 can be 255 characters long, but " 」" U+20BB7 can only be 127 characters long.)

The password contains characters that cannot be properly translated into the Microsoft Excel Macintosh version.We recommend that you use alphanumeric characters (a-z, 0-9) and symbols (!, @, #, $, %, ^, &, *, (,), +, =) for passwords.

*Not all character types were tried except ASCII printable characters.There may be exceptions.

I was able to open it in the online version of Office.I have not checked the Mac version of Office or Office Mobile.The write password was the same as the read password except for up to 15 characters.

As an internal implementation, UTF-16 will accept any characters, but if you are concerned about compatibility, it would be safe to keep only ASCII printable characters.

Word and PowerPoint are the same OpenXML specifications, so they may be the same, but Access has a completely different data format, so it may not be helpful.