I have tested only Tradeogre which now has implemented the slatepack method. Until now, Bitforex hasn’t and Gateio hasn’t, but they promise to support it.
I just hope there is an easy way to get GRIN, whether it’s on dex or centralize exchange, and the pair I need is here: Fiat gateway stablecoins list Many exchanges have USDT pairs but that means after depositing in local currency, one has to convert to USDT and then exchange it for GRIN. Ahaha. Maybe @JackZhang can make it happen because financially there is no problem for him. 
Regarding the Android wallet it can be used either ironbelly or grin++ and in the future along with updates, the existing bugs are also fixed.