Disclaimer: I am a STEM Ambassador (volunteering position) in West Sussex, working with local schools and libraries on IT projects, including using the Raspberry Pi.
The Raspberry Pi isn't a giveaway item and so schools need to make an investment in hardware or obtain sponsorship to kit out their STEM resources with them.
1M BBC micro:bits were distributed free to Yr 7 pupils as part of a project in 2016 - schools had to register/apply at the time, so if your school did not participate their pupils would not have received anything, however, as you have mentioned, other sponsorship also made units available.
Best have a word with your school's STEM/Technology people to see how they are supplementing your children's curriculum with technology resources.
The Raspberry Pi isn't a giveaway item and so schools need to make an investment in hardware or obtain sponsorship to kit out their STEM resources with them.
1M BBC micro:bits were distributed free to Yr 7 pupils as part of a project in 2016 - schools had to register/apply at the time, so if your school did not participate their pupils would not have received anything, however, as you have mentioned, other sponsorship also made units available.
Best have a word with your school's STEM/Technology people to see how they are supplementing your children's curriculum with technology resources.