theoretically possible
Specific?
Ok maybe say you have a user interface (website) that accept two numbers from a user... having withness the latest power of macrodroid, is it possible to pass this numbers to macrodroid to process (mathematically speaking) and return a result to the user? more like calculator but using macrodroid as the backend processor instead of the usual python and the like languages.
On a normal website you could simply use JavaScript to make the math for you. Browsers support executing JavaScript (they have JavaScript interpreter built-in), but browsers don't supports "executing MacroDroid", so if you want to process some data in MacroDroid you would need to send it to an Android device that does support "executing MacroDroid" and then send the response back to the website. And what would you use for sending the data to MacroDroid? Javascript. Or any other language that is supported by the browser interpreter. And how would you send the data back? If want directly you would need to run a server that can receive HTTP request, or you could use service like ntfy.sh as a kind of proxy.
Simply put, you can't directly "execute MacroDroid" on a website because the browser interpreters don't support it and MacroDroid is not even a regular language.
Sending data to be processed in MacroDroid is possible, but it would be really slow/impossible to use in most cases. MacroDroid cannot manipulate elements on the website and cannot read their properties, values etc...
I recommend you to start here:
HTML (HyperText Markup Language) is the most basic building block of the Web. It defines the meaning and structure of web content. Other technologies besides HTML are generally used to describe a web page's appearance/presentation (CSS) or functionality/behavior (JavaScript).
developer.mozilla.org