there might be another way: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7532752/

Abstract

Tight-fitting filtering facepiece (FFP3) face masks are essential respiratory protective equipment during aerosol-generating procedures in the coronavirus disease 2019 (COVID-19) environment, and require a fit test to assess mask–face seal competency. Facial hair is considered to be an impediment for achieving a competent seal. We describe an under-mask beard cover called the Singh Thattha technique, which obtained a pass rate of 25/27 (92.6%) by qualitative and 5/5 (100%) by quantitative fit test in full-bearded individuals. Sturdier versions of FFP3 were more effective. For individuals for whom shaving is not possible, the Singh Thattha technique could offer an effective solution to safely don respirator masks.