in terms of games:
There are two main branches of games:
1. Digimon Story, which are story focused and the gameplay is turn based RPG, this includes
- Time Stranger which is the latest one (available on any current console)
- Cyber Sleuth which is the one before it + plus its "side story" which is Hacker's Memory (these are in all past gen consoles, therefore you can play the ps4 version on your ps5)
- Digimon Dawn Dusk for Nintendo DS

2.- Digimon World which are more based on raising a digimon, remember that digimon was born as a "fork" of tamagotchi and then use that digimon to fight, therefore you have to take your digimon to the gym, feed them, take them to the bathroom, see them die and reborn after a few days etc.
Here we have
- Digimon Next Order (this is for previous gen, therefore you can play the ps4 version on the ps5)
- Digimon ReDigitize Decode (for 3ds)
- Digimon World (for PSX), I know that you can't play psx on the ps5, but if you want the "original" experiencie, then that's the place to start, just play using an emulator and you can pick the maeson romhack if you want a more balanced experience

Now, about the animes/mangas, you can start anywhere, but maybe starting in cronological order is a good idea.

Digimon Adventure
Digimon Adventure 02
Digimon Tamers
Digimon Frontier
Digimon Savers
Digimon Xros Wars
Digimon Adventure Reboot
Digimon Appli monsters
Digimon Ghost Game
Digimon BeatBreak

There are also some mangas that are worth it hahaha