I think if you put it before the topic ID at the end there’s no problem… but you can’t add more slashes or other delimiters.
Maybe you can use underscore to delimit if you need it, e.g. these two links go to the same place without any problem:
https://meta.discourse.org/t/topic-url-to-include-its-category/39996
https://meta.discourse.org/t/_support_topic-url-to-include-its-category/39996
your URL with question mark at the end might work - seems to work here. Not sure what the effect of that is.
https://meta.discourse.org/t/where-can-i-create-tags/31094/?category=support