Why FAT16 and FAT32 on USB sticks wont open in macOS Sequoia?

To put some context to Fat 16 and Fat 32

FAT 16 was introduced in 1987 with DOS 3.31, while FAT32 was introduced with Windows 95 OSR2(MS-DOS 7.1) in 1996.

You might better off reformatting the " Sticks " in a format of your choice, using an Apple Macintosh Computer

File system formats available in Disk Utility on Mac

Erase and reformat a storage device in Disk Utility on Mac

Windows-compatible formats

Choose one of the following Windows-compatible file system formats if you are formatting a disk to use with Windows.

• MS-DOS (FAT): Use for Windows volumes that are 32 GB or less.

• ExFAT: Use for Windows volumes that are over 32 GB.

I can't say that Sequoia can read and write to FAT16 drives, but Sequoia can read and write to FAT32 drives.