But how will the Habsburgs allow that ,they were allied to Spain and i don't want the Spaniosh to accept Mexican independence even in my timeline
Then that's a problem since the duke of Teschen was considered/offered the post OTL IIRC. But working from that offer as a baseline, it seems if they couldn't get a Spaniard they wanted someone who at least had Spanish blood. The Borbons were all prohibited from accepting by Fernando VII (which cuts out a swathe of candidates - like Leopoldo, prince of Salerno who got stopped by the British/French at Gibraltar from heading to the Americas after the Abdications of Carlos IVVand Fernando VII; or the duke of Lucca (i.e. Parma) who might be happy to trade his postage stamp sized Italian territory for a kingdom in the New World.
Still, if we look at half-Spanish members of the various dynasties that aren't Borbon, we have:
The children of João VI of Portugal and his wife, eldest daughter of Carlos IV, Carlota Joaquina. (Pedro would suit, not so much Miguel who might be too conservative for the liberales)
Carlos IV's other daughters all married Borbons so would be covered by Fernando VII's blanket edict.
Pedro Carlos of Spain and Portugal - the son of D. Gabriel (brother of Carlos IV). Technically a Borbon but raised at the Bragança court for the last while. Dead in 1811 from an attack of yellow fever that could be butterflied. Married to the eldest sister of the Emperor of Brazil. Apparently a good naval/army officer.
Any of the beothers of Emperor Franz I of Austria (all are children of Carlos III's daughter)
The duke of Modena, who's married to Princess Maria Beatrice of Savoy (granddaughter of Maria Antonietta of Spain, youngest daughter of Felipe V). Although the duke is an ultra-conservative and Maria Beatrice not much better.
Leopoldo or a surviving Pedro Carlos would be my candidates.