Uploading VeraCrypt file via browser

I want to use VeraCrypt for long-term cloud backups (Proton/Google Drive) by uploading the single container file directly through Firefox. I have no desktop sync apps installed. I’m anxious about this because a past attempt with Cryptomator failed. I had uploaded everything on Google Drive (copy + paste, using Firefox) and reset my PC, only to spend hours failing to recover my data. If I download this single VeraCrypt file from a browser onto a different PC years from now, will it decrypt perfectly with just the password? It worked when I tested it in a VM, but I need absolute certainty before relying on it.