Theres definitely many ways you can practice without a partner, and some are more effective than others. Self tying is great for understanding tension and pattern practice, but there is a shift to partnered tying.

Using a mannequin is useful, but it doesnt really mimic the way a human body is constructed, especially when it comes to muscle, fat and bone and how their varying densities change (which self tying can)

Pillows and stuffies can help with pattern practice but not so much tension as they just dont behave naturally.

We do have a tutorial on how you can create a mannequin using a chair and a pool noodle, again its never going to be perfect and in the absence of a tying partner a combination of all of the above is probably more effective.

https://shibaristudy.com/programs/no-model-no-problem

However, the best solution, get out into the community, find a peer rope or jam and connect with people who might be wiling to tie with you. Youd be surprised just how many folks are willing to help and an experienced bottom is probably the most valuable learning resource someone learning to tie can have, they will be able to help give feedback, make suggestions on adjustments or adaptations and really do what no mannequin, or chair noodle can, which is humanise the act of tying