Can dry pre ejaculation on your fingers get a girl pregnant if you finger her?

YES!: It may feel dry but this pre-ejaculation stuff (pre-cum) is seminal fluid which can contain live sperm. While, on one hand, this "dry" pre-cum contains fewer and usually older sperm than does ejaculation fluid, it takes only one hardy survivor to cause conception. If you are in a serious relationship, you 2 should discuss her using a reliable form of contraception.

Theoretically possib: It is theoretically possible but is less likely. Pre ejaculate does contain small amount of sperms. Depends if he wiped his finger and how long it was on his finger. But as I said it is very unlikely but remotely possible