The best way to privately contact me is via email. My email is firstname.lastname@example.org, please be descriptive about what you want as I’m unlikely to reply if someone were to email me “help I have a problem.” with no further info.
I am also very active on both the Universal-Team and DS⁽ⁱ⁾ Mode Hacking Discord servers, since most of what I do online relates to one of those two communities I would recommend simply joining the Discord server and asking in the relevant channel if your reason for contacting me relates to projects under one of those communities. My account is Pk11#3666 and I typically use the nickname Evie. I am also in the GodMode9, FlagBrew, CFW.Guide servers, though I would not recommend joining those specifically for the purposes of contacting me. I will not accept friend requests/DMs unless I know you, use the public channels or email me.
Most of my projects also have GBAtemp threads so that is another good way to contact me about them. 5 posts are required to initiate a DM on GBAtemp however, so unless you are already a member better to email me for private messages. I also have my DMs (not chats) open on Reddit (u/Evie_11), so that works too.
I also have a dumb little BBS page I made for fun if you just do not have accounts lol