I have multiple smaller Pico projects under my belt, but I understand that does not correlate 100% with the embedded field. Personally, from my perspective, it would feel like the equivalent to someone building a static HTML site and applying for a full-stack position, but I don't know how to fix that.
The Web Dev field and Embedded field feel extremely different, so I have the fear that with the current job market, even if I commit fully to ensuring my personal portfolio shows a lot of embedded programming, that I won't be trusted for professional projects.
I'm an embedded guy, the advice above is a reverse of what I've done in the past for clients: I wrote the embedded device firmware and dabbled a little in using .NET to create a portal for the customer to view and manage data from a fleet of devices reporting things like timestamp, battery level, temperature, etc.
The key skill is C. Most everything else can be learned on the job, and will differ from project to project.
Obviously not all embedded programing is in C (although a lot is) but folks proficient in C are typically quick to pick up other languages.
So from a resume-bolstering point of view I'd suggest getting a Raspberry PI (or similar) and build some C projects on it. That would expose you to a lot of embedded skills. Bonus points if you choose a device either severe memory and/or cpu constraints.
Changing specialties is rough, but I have done it more than once. Embedded is a strange space, but you can break in.