What’s the easiest way to preserve a few WhatsApp chats as local web pages?

A local HTML page is definitely feasible. An HTML file can contain the exported messages, while links such as Photo point to folders containing the pictures and videos. You can open the file directly in a browser without publishing it online. If you want to learn some basic web development, this would be a manageable project, though entering and formatting everything by hand could take time.

Start by using WhatsApp’s built-in chat export feature. It can save a conversation as a text file and, if you choose, include the attached media. That may be all you need and is much simpler than building a website from scratch.

You can also use a small offline chat-to-HTML converter. Export the conversation first, then run the converter according to its instructions; it can usually format the messages and connect the media files for you. Keep the exported chat and media in the same folder structure so the links continue working.

You don’t need to install a web server for a simple personal archive. A static index.html file and a folder containing the message data and media are enough. A server is only useful if you want more advanced navigation or if your browser blocks something when opening files directly.