To convert HTML to Google Slides you go through images, through a PowerPoint file, or through a link, because Slides has no HTML import. There is no menu item that takes markup and produces slides.

That sounds like a limitation and is mostly a format difference. A web page is one continuous column of unknown height. A deck is a fixed sequence of fixed size frames. Nothing maps automatically between them.
Below are the three routes that work, what each keeps, and the case for not building the deck at all.
Ways to convert HTML to Google Slides
| Route | Text stays editable | Looks like the page | Charts | Effort |
|---|---|---|---|---|
| Image per section | No | Yes, exactly | As pictures | Low |
| Convert to PowerPoint, then import | Yes | No | No | Medium |
| Rebuild by hand in Slides | Yes | No | Rebuilt | High |
| Keep the page, link from a slide | At the source | Yes, live | Yes, working | Lowest |
Choose by what the deck is for. A deck that gets sent around needs editable text. A deck you present once needs to look right.
The fourth row is not a conversion at all, and it is on the list because it is often the correct answer. A page that already works does not need to become slides to be presented.
Route one: one image per section
The fastest route, and the one that preserves the design exactly.
- Split the page into sections. One idea per section, each fitting a landscape frame. A long page is usually four to eight.
- Capture each section. HTML to image does this without a screenshot tool, at a resolution that stays readable on a projector.
- Insert one image per slide. Size it to fill the frame.
- Add a plain text title to each slide. This is what makes the deck navigable in the slide sorter and in search.
- Hyperlink each image to the live page. One click during the talk reaches the working version.
The cost is real. The text in those images cannot be edited, searched, translated or read by a screen reader, so the titles you add in step four are doing more work than they look like they are.
Capture at twice the size you need. A projector and a large monitor both show detail that looks fine on a laptop screen and turns soft once scaled up.
If a section is taller than a landscape frame, split it rather than shrinking it. Text that has been scaled down to fit is the most common reason a deck is unreadable from the back of a room.
Route two: through a PowerPoint file
Slides can import from a .pptx, so producing one gets you editable slides.
Pandoc will build a deck from structured content, using top level headings as slide breaks:
pandoc deck.html -o deck.pptx
Upload the result to Drive, then use File, then Import slides in a Slides presentation. You choose which slides to bring in, so a long deck can be imported in pieces.
Expect plain slides. Pandoc reads structure, not your CSS, so you get titles and bullets on the default template.
That is a reasonable starting point when someone else will style the deck, and a poor one when the design was the reason you had a page in the first place.
Route three: keep the page

Worth asking before you spend the afternoon: does this need to be a deck?
A page scrolls, works on a phone, keeps its charts interactive, and can be corrected after it is sent. A deck does none of those, and in exchange it gives you pacing and a fixed frame for a room with a projector.
If the audience will read it on their own, the page is the better artefact. Turning a slide deck into a link covers the same argument from the other direction.
Paste the HTML into a NOS document and it renders as written, charts and scripts included, as a page of its own.

Then Share, then Share link, then Create link. The link is unlisted by default, so it opens for whoever holds it without being indexed.

The hybrid that usually wins
In practice most people need both, and the combination is short to build.
- A deck of six image slides for the meeting, so the room sees the same thing you do.
- Each image hyperlinked to the live page, so a question can be answered from the real numbers.
- The address written in the speaker notes, as a fallback when the click fails.
- The page corrected afterwards, without rebuilding the deck, because the links point at an address.
Embedding an HTML link in PowerPoint covers the same pairing in Office, including the add-in that loads a page inside a slide and the reasons it fails.
Build the deck last, once the page is settled. Rebuilding six image slides after every correction is the main reason people abandon the hybrid halfway through.
What never converts
Regardless of route, these do not come across into any deck:
- Sorting, filtering and expanding table rows.
- Hover states and tooltips on charts.
- Anything that loads data when the page opens.
- Layouts built with media queries, since a slide has one fixed size.
If those are the reason the page exists, the deck is a summary of the page, not a replacement for it. Treat it that way and both artefacts stay honest.
For the document equivalent of this question, see converting HTML to a Google Doc.