I like the FFXIV approach of making a daily feature where players can join a random group doing content with equalized gear for boosted rewards.
Similar to what we have now with the challenge guardians/abyssal dungeons, except a daily thing to help fill content newer players would struggle to find fills otherwise.
This would require making said content equalized by default, and make equalizing not ruin relic sets or stat thresholds, but it could get people playing together and make the early game not so dead. Would also give variety to endgame players killing Deska or kunga every day till boredom.
For tier 1 just do the tower for leapstones, and send dispatches for it in your stronghold to get some leaps.
For tier 2:
That’s your friend. You get so many materials you do not have to do guardian raids at all, or just dispatch and tower if you want more, but just those 2 challenge abyss dungeons gives so many it’s your go to. Also you said you are in EUC, you could make a party in the party finder and ask for help (ye it’s just a free boost and u aint playing, but an option nonetheless.) often people help around.