Q.Oyster Mushrooms Not Fruiting
Hello, I planted 1kg of oyster mushroom spawn along with 4 kg of wet substrate. It has been 16 days and although the mycelium has completely taken over the substrate, I don’t see any pins developing. I’ve kept the temperature in the room to 25oC and the humidity level is 70% . I am attaching a picture for reference.. hope yo hear back soon

Certified GKH Gardening Expert
Those jars appear to be sealed. Pins cannot form unless it is exposed to fresh air (the more accurate term is CO2 exchange). With that small amount of substrate, it will be important to spray it with a fine mist several times per day. If all goes well, you can expect to harvest half of your initial substrate weight worth of fruiting bodies (also depending on substrate make up).
As a cultivator, myself, I prefer a humidity controlled tent. This can be as simple as a horticultural greenhouse tent and a fogger in a jug of water, with a fan blowing inside. Hooking this up to a cheap humidistat will automate the process. It doesn't have to be that intense, though. It can be as simple as a tote with holes in it, and perlite in the bottom, kept saturated with clean water.
Here is an article that will help you to set up a simple fruiting chamber:
https://www.gardeningknowhow.com/edible/vegetables/mushrooms/making-a-mushroom-fruiting-chamber.htm
This collection of articles will offer more information on mushrooms:
https://www.gardeningknowhow.com/edible/vegetables/mushrooms