In the main Star Trek universe, most Starfleet officers that we meet attend Starfleet Academy in San Francisco before receiving their first commission in Starfleet as an Ensign, but Michael Burnham apparently entered Starfleet after attending the Vulcan Science Academy instead. Are Starfleet Academy and the Vulcan Science Academy the only two regular educational options for a Starfleet officer's career, or can one attend pretty much any university in the Federation and then apply for a Starfleet officer's commission?
In our own world, the US military works very much like this - there are a small number of federally-run service academies, but one absolutely can plan on attending a state or even private university with a plan for seeking an officer's commission after graduation.
We know that there are several other universities in existence in the Federation - Cambridge University in England apparently still exists in Picard's time (I guess it's been a good 1200 years), and we also learn of the (in-universe) Pennington School in New Zealand that Jake Sisko considers attending.
To be clear, it's possible to get a field commission without any formal higher education through some combination of being a genius and your mom being in bed with the captain, but I'm asking about standard career paths for the average Starfleet wannabe - someone who has what it takes to meet the basic requirements but isn't anyone special.
So, if I'm a random Federation young person (smart, but not too smart, social, but without high social connections, brave, but not super-brave) who really wants to serve as an officer in Starfleet but would prefer to go to college on Andoria, is this possible? Alternately, could Jake Sisko have sought a commission after graduating from Pennington? A big part of Jake's character is not wanting to follow in his father's footsteps, so it's unlikely he would choose to voluntarily seek a commission, but would going to Pennington instead of Starfleet Academy essentially mean no real possibility of a commission, or just some extra effort taking Starfleet-ROTC courses on the weekends when his friends are at the bar?
My focus is on the Prime universe (not the Abramsverse), but I'm not picky on the era. If there is some random TOS redshirt Ensign (clearly no one special, but an officer nonetheless) who mentions, "No sir, I didn't attend the Academy! I went to the Advanced Stellar Cartography Institute of Risa with a major in Planetary Survey Management.", that would be a great answer.
If graduates of the Vulcan Science Academy are not normally eligible for commissioning in Starfleet and Michael Burnham's commission was specially obtained through political pressure from Sarek, that would be an answer as well.