Here’s what I found.

Count
143,859.¹
Full table: https://unicode-table.com/en/#basic-latin
Methodology
This short article assumes that by now, every useful/usable/commonly-used character has been encoded and added to the unicode standard.
This is not necessarily the case. In fact, “Unicode standard doesn’t freeze, it continues to evolve.”²
Definitions
Character (computing): In computer and machine-based telecommunications…
Here’s what I found.

Count
97.
Entire lit: https://github.com/aa-ag/counting_stuff/blob/main/http_status.txt
Definitions
HTTP: The Hypertext Transfer Protocol is an application layer protocol for distributed, collaborative, hypermedia information systems.¹
(HTTP) Status Codes: are issued by a server in response to a client’s request made to the server. It includes codes from IETF Request for Comments (RFCs), other specifications, and some additional codes used in some common applications of the HTTP. The first digit of the status code specifies one of five standard classes of responses. The message phrases shown are typical, but any human-readable alternative may be provided. Unless otherwise stated, the status code is part of the HTTP/1.1 standard (RFC 7231).²
Methodology
A little Python and a lot of curiosity go a long way:
Here’s what I found.

Count
1635.
Entire list: https://github.com/aa-ag/counting_stuff/blob/main/formats.txt from https://en.wikipedia.org/wiki/List_of_file_formats
Definitions
A file format: A format for encoding information in a file. Each different type of file has a different file format. The file format specifies first whether the file is a binary or ASCII file, and second, how the information is organized.¹
Methodology
A little Python and a lot of curiosity can go a long way: