Pinterest & Tumblr for Branding (in addition to IG)?

I use IG at the moment for sharing quotes for a charity/public figure I’m promoting, and it is essentially used for ‘branding’ by people seeing the quotes and person’s face (and not sales/fundraising/conversions).

I figure I may as well expand that to the other platforms made available, so I’m curious about Pinterest and Tumblr. I’ve done a bit of reading and know I can do more (though it seems it’s much less talked about than IG), so I’m just wondering what some common methods might be for my purpose of simply branding and not for sales.

My IG accounts are just designed to follow/unfollow (plus other tools) and build up the accounts and share less than or up to 1/3rd of the material to come from the charity/public figure and the rest being other popular content from that niche, so people who like the other stuff become exposed to what I’m trying to share. So do Pinterest and Tumblr similarly work well for building accounts in this way? Are there other good methods for exposure and growth on these platforms? Just wanting to see if it would be a fairly similar strategy.