Mostly males. I’m French and "Claude can be female" is a almost a TIL thing (wikipedia says ~5% of Claudes are women in 2022 — and apparently this 5% is counting Claudia).
Aleksandr (diminuitive being Alyosha) is male. Aleksandra (Sasha) is female. I've never heard anyone male or female called "Aleksa". Perhaps in some regional dialect but doubtful. There's Alik (pronounced AH-l'eek) as a shortened form for some middle-aged men in russian-speaking central asia, and Oleg in russia (pronounced ah-L'EHG).
In the russian diaspora in the US, Alex is pronounced AH-leks. If there was an analogous Alexa (there isn't) the pronunciation would be ah-LEK-sa like the service.