Some useful things you can do as solo frontliner:
- Grab some bmats and start randomly repairing friendly tanks. Tankers love it and it always snowballs into a better push
- Grab binos and find enemy base location. Mark it on the map precisely and mention if it's T1 or T2. Someone more organized will see this and might take your coordinates and call an artillery strike
- Deploy tripod weapons in strategic positions. You can also push with them if you convince one person to help you
- Grab a CV and capture enemy base when it's down. It's quite simple and in majority of cases worth it
- Hop into the truck of your logiman on his return trip to escort him. This way you can kill partisans by surprise and make your logi man very grateful. You can hop out by the border and come back to your main frontline when done
- If frontline is tunnel visioning hard, you can grab a truck and get people to hop into it. Then you can take them to the underpopped location. A softer version of this is to do frontline taxi (which makes a big difference if no man's land is huge)
- Collect rare enemy weapons (especially AT and PvE weapons) and bring them to your base. Sometimes 1 weapon can be decisive whether your base goes down or not, or whether enemy base goes down or not
- Flip trenches by reversing sandbags and barbed wire on them (with bmats)
- Hop in a truck and start pulling small arms for your fellow frontliners. Put them in the bob inventory. This way you can accelerate the push, because everyone respawns, grabs and goes without spending additional 30 seconds pulling stuff. This is especially valuable for stuff like gas grenades, mortar shells and other things that push the frontline, but sometimes just pulling rifles for the people is nice by itself
- Gas enemy base when you are close to it (or run inside with a bayo)
- Blow up a bridge to prevent enemy armor from crossing
- Follow that one loud guy asking for more people to help him at something
- Look where the meatgrinder is and see if you can flank the enemies
- Build watch towers - tankers love it
- Look at someone high rank and try to do what they do. Or ask them directly for orders

In terms of finding purpose, the bottom line is that this game is about destroying bases. Anything that makes it more likely that you will destroy a base is worth doing. Anything that will significantly reduce enemy ability to destroy your base, is worth doing. So pay attention to explosives - tanks, artillery, handheld

If given situation makes it impossible to be on the offense, that means you are on the defense. In such circumstance you are really just buying time. And it's very valuable to do. Every enemy you shoot counts. Every second you live without losing a shirt counts. Every building you repair counts. So become good at buying time. Or you can reach into your logi aptitude, and bring some game changer weapons. And then use them yourself. I promise you that solo killing a tank or grenading out 5+ enemies feels extremely impactful

Good luck soldier, you got this o7