Arkady Dvorkovich
Perhaps worth starting with Dvorkovich's announcement here on Friday 13th May two days after FIDE made their official call for candidates. Dvorkovich is certainly not taking this lightly. His heavyweight team includes former World Champion, Vishy Anand, as his Deputy President and GM Zhu Chen as Treasurer.
However, first out of the blocks on 30th April, almost two weeks before FIDE's call for candidates was:
Enyonam Sewa Fumey
More of a politician than a chess player (despite being a Candidate Master his all-time highest rating is 1870), he became President of the Togo Chess Federation in 2017 and shortly after was part of Dvorkovich's successful campaign becoming FIDE General Secretary. So he is actually running against his boss. His candidacy is reported on the FIDE website here.
Update: According to this ChesscomLive tweet:
Enyonam Sewa Fumey from Togo won't be among the FIDE presidential candidates as he could not get the necessary support from at least one federation in Europe.
Inal Sheripov
With a 2290 rapid rating (no standard or blitz) from a one-off tournament (the 2018 Belgium rapid championships) he is more of a film maker and politician than chess player. Although he was a strong Chechen player in his youth. There are more details about him and his candidacy here. Not very encouraging is this:
The first vice-president on Sheripov's team is Lewis Ncube (Zambia), a well-known FIDE official best known from the Ilyumzhinov era
...
Ncube was the only one who voted against Ilyumzhinov's resignation at the FIDE Council meeting in spring 2018
Andrei Barishpolets
A young (31) Ukrainian GM with no political experience, he looks very much like an outsider. FIDE is not Eurovision. His manifesto is here. Summary - "definitely not related to Dvorkovich, nor Ilyumzhinov, nor the Kremlin".
Update: With the inclusion of Peter Heine Nielson, one of Magnus Carlsen's seconds, in his team he becomes less of an outsider. Getting the backing of the World Champion also counts for something:
Chess federations of the Americas! Can one of you please pledge your support to the Baryshpolets/Nielsen ticket so @PHChess can focus on prep instead?