Update and document GPU buffer handling #2893

Job	Run time
doctests	1m 11s
py=3.11-min_deps	3m 23s
os=ubuntu-latest, py=3.11, np=1.25, deps=minimal	5m 46s
py=3.13-upstream	5m 32s
os=ubuntu-latest, py=3.11, np=1.25, deps=optional	5m 41s
os=ubuntu-latest, py=3.11, np=2.1, deps=minimal	5m 37s
os=ubuntu-latest, py=3.11, np=2.1, deps=optional	5m 36s
os=ubuntu-latest, py=3.12, np=1.25, deps=minimal	6m 15s
os=ubuntu-latest, py=3.12, np=1.25, deps=optional	6m 14s
os=ubuntu-latest, py=3.12, np=2.1, deps=minimal	6m 6s
os=ubuntu-latest, py=3.12, np=2.1, deps=optional	6m 26s
os=ubuntu-latest, py=3.13, np=1.25, deps=minimal	9m 17s
os=ubuntu-latest, py=3.13, np=1.25, deps=optional	9m 10s
os=ubuntu-latest, py=3.13, np=2.1, deps=minimal	6m 15s
os=ubuntu-latest, py=3.13, np=2.1, deps=optional	6m 14s
os=macos-latest, py=3.11, np=1.25, deps=optional	3m 54s
os=macos-latest, py=3.13, np=2.1, deps=optional	4m 35s
os=windows-latest, py=3.11, np=1.25, deps=optional	9m 56s
os=windows-latest, py=3.13, np=2.1, deps=optional	8m 40s
Test complete	1s
	1h 55m 49s

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