“Equip planeswalker” is a variant of the equip ability. “Equip planeswalker [cost]” means “[Cost]: Attach this permanent to target planeswalker you control as though that planeswalker were a creature. Activate only as a sorcery.”
June 18, 2021 · Modern Horizons 2
rule 702.6e not present in this release
April 27, 2018 · Dominaria
If a permanent has multiple equip abilities, any of its equip abilities may be activated.