Aside from installing veraPDF, you can validate PDFs compliance with:
- the online veraPDF demo: https://demo.verapdf.org/
- (offline) the docker image: https://hub.docker.com/r/verapdf/rest
- Online alternative with a french institution: https://facile.cines.fr/
The last one is actually used to validate >=PDF 1.4 compliance for all french PhD theses.