When I fancy serving jam, I just put ripe strawbs into a little pan with a tiny amount of water, cook them a few minutes, mashing them down when soft enough. I find strawbs taste sweeter when cooked so I don't sweeten them. I do the same with rasps and might add a little stevia to taste. Mine always gets eaten within a few days, so I just store it in the fridge. It's so quick to make that there's no need to make a big batch. I guess it would freeze OK, but I just freeze the raw berries.

My go-to sweetener is stevia, but stevia is noticeable if too much is used, so if I wanted to make it a bit sweeter, I'd add a small amount of a second different sweetener - e.g. Splenda, eurythritol, etc.