I've been using an Fdroid browser; Lightning on my Android tablet. If some kind soul could port it, many would be grateful.
It's on Github. I'm brand new (yesterday) to UB Ports or I'd give it a stab myself.

Another F-Droid app: K-9 Mail is open source, light and fully featured.

@Bramble The tablet I'm typing on has far lower specs than the Pinetab. There are only a few apps I use on on the spyware named Android.