I don't know it is about some parts of this forum being so toxic, especially when people are asking questions. Don't assume everyone has the same knowledge as you.
It would depend on the engagement as to whether you should use something more professional to deliver (like Pixieset/Pictime/website gallery) or use something like Google Drive/Dropbox and providing a link to download. If they are not paying you/are paying little then it might not make sense to invest in something like Pixieset/Pic-Time. If this is a regular thing and the money you are being paid more than covers it then go for it.
From what I remember from your website critique post, you are using Squarespace for your website? I don't believe they offer photo proofing galleries. But you could create a new unlinked (unlinked meaning it is not in the navigation menu and only reachable if you have the link) and password protected page. On this you could include a gallery of the photos for your client + a link to download the full res files from Google Drive/drop box.