Privacy-wise your calls and SMS can still be spied on, and you can still be tracked by GSM Triangulation since the phone is capable of 4G.
Also afaik it runs Mocor which is designed for dumb phones, and I’ve read somewhere that Mocor was an Android 4.4 fork or something like that, but APKs won’t start/run.
I host https://proxigram.kyun.li and it is currently down, will work again soon :)
EDIT: Instance is working again