Players with 2+ Majors on hard courts (in no particular order):
(1) Federer; (2) Djokovic; (3) Nadal; (4) Wawrinka; (5) Safin; (6) Rafter; (7) Agassi; (8) Sampras; (9) Courier; (10) Becker; (11) Edberg; (12) Wilander; (13) Lendl; (14) McEnroe; (15) Connors.
Then, you have players like Medvedev, who had 1 hard courts Major. Again, in no particular order:
(1) Sinner; (2) Alcaraz; (3) Thiem; (4) Cilic; (5) Murray; (6) del Potro; (7) Roddick; (8) Hewitt; (9) Johansson; (10) Kafelnikov; (11) Korda
Then, you have great hard court players who played most/all of their careers before hard court Majors like Laver and Newcombe.
Setting aside the older guys like Laver and Newk, I'd have Medvedev behind the 15 players with 2+ hard court Majors. The question then becomes how he compares with the other players who won 1 hard court Major. He's currently ahead of Sinner and Alcaraz, but they have plenty of time to pass him. I'd also have him ahead of Thiem, Cilic, Johansson, Kafelnikov, and Korda.
That puts Medvedev in the 16-20 range, behind the 2+ Major winners and in competition with Murray, del Potro, Roddick, and Hewitt. I'd have to think about how he measures up to them.