Agreed. Tangentially: Although many of the creators, maintainers and board members of Palomar have a background in Lean, the project welcomes alternative proof

Agreed. Tangentially: Although many of the creators, maintainers and board members of Palomar have a background in Lean, the project welcomes alternative proof assistants, see "What about other proof assistants?" on the about (https://palomar-registry.org/about https://palomar-registry.org/about) page. From what I can tell, many in the mathematical community lament the predominance of Lean, but it reached some sort of critical mass (ecosystem, size of library) that makes it very hard to compete with - e.g. find someone who volunteers to support an alternative on Palomar, with all that this entails.