Say I want to help a little and run a I2P 24/7 node. Only 1 problem: Sometimes I use VPN.

Not for privacy (VPNs are not for that) but... to download Linux ISO's.

Will that hurt my integration into the I2P network? will that make my traffic more finger printable?

I can't post this question on reddit(the place where most users are) unless, ofc, you want to sell your account for monero.