Speeding up boot times on the GameShell?

My GameShell takes 20 seconds from power-on to get into the launcher - using OS v0.5, USB-Ethernet enabled, using the latest LauncherGo. I would like to cut that time down to 10 seconds or less if possible, similar to my Game Boy Advance with a flashcart or homebrewed Nintendo 3DS. Does anyone have any help or advice they could give?

systemd-analyze only reports the boot taking 11 seconds. I’m not sure when it starts keeping track, after the “AH~clockwork” and goggle-penguin splash screens, after the “HAPPY HACKING” text prompt, does it count the launcher loading? Is there a way I could cut out the splash screens to cut boot time?

I also saw various custom OS builds around the forum and their guides and notes on building the OS. Would building an OS myself (say Armbian) let me speed up boot?