You can do this now. You can find the Block number under the settings section of that block editor box. Then you just add taht block number to the end of that pages URL

ie: https://www.churchname.org.au/serve#block-529 will take you to a specific block on the serve page

How can you discover what the block number is?

It's You can also inspect the webpage HTML in your browser to find the block number and then create a link to the block instead of the heading. For instance, if you know that the block number is 46, you can link to /pagename#block-46 and when they click that link it will take them to that block. https://christianretreat.org/donate as an example; the big "online, text, mobile, cash/check" icons take you different places on the same page. But yes, I agree a more user friendly tool would be nice.

Just a note: you can do this yourself now, as long as you know a teensy bit of HTML:

(1) Create your headings using the 'Heading' or 'Subheading' option in the formatting bar.

(2) Click the '<>' button in the formatting bar to view the raw HTML of the page. Find your headings - they will start with <h2> (headings) and <h3> (subheadings).

(3) For each heading/subheading you want to link to, add id="someUniqueName" to the <h2> or <h3> tags, so that the end result looks like <h2 id="someUniqueName">. Each id on a given page should be unique, and id should not include spaces. Once you've added your ids, you can close the raw HTML viewer by clicking 'OK' to save your changes.

(4) Finally, up at the top of the text, create your links to those headings/subheadings: Create the text you want to click on, then highlight it and click the 'link' button in the format bar, and in the URL field, type #someUniqueName (obviously using the appropriate id you added back in step 3).

Hope that helps, until it's added as a more user-friendly tool in the toolbar.