“External Sites' evil twin” -- me, probably
NextFrame is a simple app based around the idea that actually, the Nextcloud topbar is pretty cool after all.
When installed, this app will create a new settings entry under /settings/admin/additional where you can generate a new "view token", which will be bound to a specific list of ancestors authorized by CSP.
You can then embed the Nextcloud top bar onto another website, preferably on the same domain to guarantee shared login cookies.
Here's an example of a recommended iframe tag making full use of Nextframe's features (requires iframeResizer.min.js):
<script src="/path/to/iframeResizer.min.js"></script>
<iframe src="https://nextcloud/apps/nextframe/disp/TOKEN" id="nextframe" style="position: absolute; border: none; width: 100%; height: 60px; overflow: hidden;" scrolling="no"></iframe>
<script>iFrameResize({autoSize: false}, "#nextframe")</script>Nextframe is explicitly compatible with iFrame Resizer and Custom Menu.
When a popover or Custom Menu is opened and iFrame Resizer is loaded, the iframe will grow to the size of the browser's viewport, allowing the entire UI to show properly. It shrinks back to its original height when the popover is closed.