It seems like Bortoleto is the favourite for Sauber now, although it could also be Pourchaire, Drugovich, Lawson or presumably Hadjar (or, of course, Bottas or Magnussen).
McLaren will, supposedly, loan or release the Brazilian ace.
Doohan only has a 1-year contract so if Doohan is poor during the season, there is still a possibility that Martins (or even Pourchaire) could be substituted for the Australian to return Alpine-Renault or Alpine-Mercedes to an all-French lineup!
If Hadjar, the F2 leader, is not considered for Sauber then it's not clear where (if anywhere) in F1 Hadjar could end up. Champion in second season wouldn't be too bad by Hadjar, would it?
It's a shame that F2 is so difficult to decipher and doesn't clearly illuminate the best candidates for F1 anymore. It's becoming a bit like Formula 3000 in that sense.