Something that doesn’t take much space or any equipment would be simply practicing solo grappling movements. This would include snake move (hip escape, shrimping) bridges, hip ups, shoulder rolls, leg windmills, sprawls, technical standup, etc.
You can do reps or combine movements. Be creative with your combinations and maybe use a litttle imagination, shadow grappling if you will.
If you have a resistance band and can attach it to something you can also practice some judo movements.
Whatever you do try and keep active and mix things up!