I just started playing pyke a lot (mainly a midlane player, play a decent bit of yasuo and also play assassins).
Biggest way to use your lead as pyke is roaming. If you get ahead botlane use it, be agressive in lane and force them back/kill one then roam mid w/ your jg if their mid backs off, cool your mid gets priority and free farm and you can help jg take dragon and enemy team can't contest.
If your mid is a champ who can solo lane in a side-lane (yasuo, ekko, assassins), try to take the botlane turret asap so you and your adc can rotate mid, this unlocks your roams even more since you can roam to both sides of the river to support your JG, or roam top/bot.
B/c of his execute ult pyke and an ally with damage will be able to have kill pressure on pretty much any enemy champ (unless theyre both super far behind), and you can easily force flashes etc.
But yeah, pyke's best way to use a lane is the same as a midlane assassin who gets ahead, roam and get the rest of your team ahead. However as i said at the start, try to avoid doing this at the expense of your adc.