Frames + Iframes
You can make "buttons" inside of FRAME that trigger a range of interactivity and actions. Turn on Edit Mode, and click on an asset like an image or a 3D model. You will see that in the Edit Menu on the bottom left you can "add a link", and you have a lot of neat options.
A very popular link type in FRAME is the "web link", which makes it so that when a user clicks on an asset with a web link, a website will open in new browser window. If you select "embed" on the switch at the bottom of the Edit Menu, though, you can pick "Embed". A link with the "Embed" switch on will make the website open up in an overlay on top of the Frame, instead of a new tab.
Try it out by putting a link to the Frame website at https://learn.framevr.io, and then turn off Edit Mode and click on the asset. You'll see a nice overlay in the bottom left corner that you can resize, minimize, and close. You can fully interact with the page too, by clicking on links inside of it, scrolling, etc.
Keep in mind that this overlay is local - which means that just because you see it doesn't mean other people see it too. If someone clicks on the link that you clicked on, they will also get the website overlay. If you close it, it only closes for you - not for everyone else that might have it open. So it's not a "synchronized" asset like some other assets are. Also, the overlay is on top of the 3D scene, but not a part of it. That's why it stays visible in the same spot even as you move around the scene.
Not all links work with this "Embed" method, because not all websites allow themselves to be embedded in this fashion. This overlay technique makes use of iframes to render the website on top of FRAME, and many websites do this lame thing where they say "I can't be put in an iframe". That said, many websites do allow this (FRAME does too, by the way!) - and sometimes you just have to do a little exploring to get the right link.
For example, just copying and pasting the link of a Miro whiteboard may not work - but if you publicly share your whiteboard and then generate its embed code, you can actually copy and paste the URL found inside its embed code and use that as the web link for your asset. In fact, many websites that let you generate an "embed code" will actually have a special version of the URL inside that code that will work inside of iframes like these.
Repeating an important point : you can't just paste in an embed code that you generate from a service, you want to paste in the URL found inside that embed code.
Finally, iframes also don't work in VR right now, because it's really tricky to render iframes inside of a 3D scene, and when immersed in VR you can't see overlays like this that aren't part of the 3D scene. This is something we'll be thinking about and working towards, but for now people in VR will be given the option to open those web links in a new browser tab if they click on them.
Good luck!