Is it advised to give a suggestion how to cite in the thesis document itself? I am thinking about including a statement as follows in my thesis (e.g. at the second page).


  Please cite this thesis as "X.Y, My fancy title, Thesis, University of XZ, June 2019, https://doi.org/10.15420/882.2249."


One the one hand this could be very helpful for someone who wants to cite the thesis. On the other hand it might come across as begging for a citation or that I prefer to be cited with a particular citation style (what I do not, of course).

Is this a sensible idea? 
If not, is there a preferred way to mention at least the DOI?
If yes, is there a better wording?
I wouldn't include this statement.  Academic authors don't need to be told how to cite theses - they already know.  And I think it does make it sound like you insist on a particular citation style, which may feel awkward to authors who want or are required to use something else.  (I don't see it as "begging for citation", though.)

It is certainly a good idea to include the DOI, but I would just write something like


  Digital Object Identifier:  https://doi.org/10.15420/882.2249


in the colophon or some other convenient place in the document's frontmatter.