If you can't find the motivation to start doing a lengthy task (like cleaning the house, gardening, or working on a project), force yourself to do it only for 30 minutes. It's not an unreasonably long time. By the end, you'll either have gained enough momentum to keep going and finish it, or if not, you've still made 30 minutes of progress.
I like how you're accepting longer tasks as well. What I've read typically is like "if a long task is dumb, get into the grind spirit by working a tiny task first and using that momentum".
Your suggestion is to just 'dip your toe into' the longer task as a taste test. I like that. And I have so many longer tasks to do.
I've heard this called the 'dirty 30'. It works. Whatever needs cleaning up or tidying, 30 minutes is just short enough to not feel like you're using all your free time on chores, but long enough to make a real dent. Especially if your partner either helps with the same task or does a different one. Setting a timer can help and you start to almost frantically see how much you can get done. I like that competitive element even against myself.
As someone with ADHD, I'm all about the 5 minute timer.
If I spend 0 minutes cleaning my kitchen, I will clean 0% of my kitchen. But if I set a 5 minute timer, I'll almost always completely finish whatever cleaning I needed to do.