I can't record both PJ64 and Livesplit at the same time cuz my PC sucks and it lags from that

I use animation software to animate my timer.

you can do that.

Yes you can, I use an Android app known as Kinemaster. Kinemaster is an animation and editing program and you can animate your text by splitting it at the play head and I also use a gradient blue background to highlight my lap times.

Or then you could record your mobile screen. Use FramePerfect (the LiveSplit correspondent for mobile devices), watch your run then do the splits. Then put it at the side of the run footage with a video editor.

Theres no need to have a timer but it helps, be sure to time it well with another tool like aviutl