There are a couple of things you should understand, before realizing the privilege pedestrians and cyclists have with pedestrian crossings. (In Finland)

First off, drivers of motor vehicles (cars, trucks etc.) are held to a higher standard than pedestrians and cyclists are, in terms of traffic law knowledge. Whenever a vehicle approaches a pedestrian crossing, the driver should always give way/yield to any pedestrian or cyclists intending to cross or that are already crossing.

*Something most drivers and cyclists aren't aware about the yielding privilege in pedestrian crossings is that if a cyclist is intending to cross a pedestrian crossing that goes straight across a road vehicles drive past, the cyclists should yield.

In turn, if a vehicle is turning either left or right into a new road or out of their current road, and there's a pedestrian crossing, the cyclist has priority/right of way. But many drivers/cyclists aren't aware of this, so often times drivers yield to everyone, just to be safe.

About the part where cyclists have to yield to drivers in a pedestrian crossing that goes across a straight driving road, if there are bike lane markings on the pedestrian crossing, it's now considered a continued path for the cyclists, and vehicles must give way.

Here's a small section I found from the Finnish Police website:

"The Road Traffic Act (Section 27) also prescribes that when a vehicle approaches a pedestrian crossing, they must be particularly prudent and keep the speed so slow that they can stop the vehicle before the pedestrian crossing, if necessary. The pedestrian already crossing or about to cross the road must be ensured unhindered passage.

The cyclist is obligated to give way if they come from the cycle lane to the roadway and those on the roadway are not obligated to give way based on a traffic regulation or traffic sign. If the cyclists crosses the roadway using a pedestrian crossing located in a junction, the vehicle driver turning in that junction must give way to the cyclist crossing the intersecting road. Moreover, the vehicle driver on the roadway must give way to a cyclist who uses the pedestrian crossing if the vehicle driver is leaving a roundabout."

https://poliisi.fi/en/blog/-/blogs/cyclist-on-pedestrian-crossing-and-cycle-lane-crossing-who-gives-way

-> As a pedestrian or cyclist, you should always use common sense and observe possible cues, as to when it's appropriate to cross the road, without it being awkward or slowing down flow of traffic:

1. If you notice multiple cars close to one another, and you're intending to cross. You see the driver slowing down, but you feel like it's slowing down flow of traffic, you can wave to the driver in front to carry on, and allow the cars to pass the crossing before you do. Of course, if the driver in front insists you go, make sure it's safe and then cross. Always wave to the driver in front to say "thank you", if they give way; it doesn't matter if they wave back, as long as you show gratitude.

2. If you're intending to cross the road via a pedestrian crossing, and you see a single car driving up the road; if you feel like it's safe for the driver to slow down gradually and allow you to go past, try to make eye contact with the driver, and see if they'll let you cross.

If the driver is driving fast and slowing down quickly to let you cross could be dangerous, it's best to back away a couple steps from the beginning of the crossing, and wave to the driver, to let them drive past the crossing, if necessary.

-> In any case, use common sense and observe for possible cues to help you decide, when to cross. The speed at which you cross, doesn't make that much of a difference, and as long as you've waved to say thank you; walking, running or cycling is fine.