Taichi and Sora are clearly best friends and trust each other a lot. However its clear Taichi see's Sora has something more than that and its
shown in 02 by him kind of asking her out.
I disagree with Matt helping Sora. Tai is usually the one who shows his care, for instance during the rescue arc he takes things very seriously, or when Sora is upset about her Crest being the one about Love. We kind of see it from Sora as well: her biggest fear is shown to be failing Tai, iirc she's the first to split from the group to continue looking for Tai.
Honestly, before that episode in 02 no one even imagined Sora and Matt together. Its why so many people hate that pairing and its probably the least favourite one in the series by far.
Also I don't know anything about these Digimon Knights other than Omnimon apparently being one....whose the strongest